Tempeh is one of those foods you’ve probably seen at health food stores or heard about in vegan recipes. Maybe you’ve even eaten it at a fancy café where it was disguised as a bacon alternative or tossed into a grain bowl. But making it yourself? That’s a whole other level of intimidating. Don’t worry. I’m here to break it down for you—step by step—because homemade tempeh is cheaper, fresher, and honestly, tastes better than anything store-bought. That’s if you get it right (see my comprehensive troubleshooting guide below.)
So, grab your soybeans, roll up your sleeves, and let’s do this.
What Is Tempeh, Anyway?
Before we dive into the “how,” let’s get clear on the “what.” Tempeh is a traditional Indonesian food made by fermenting soybeans with a mold called Rhizopus oligosporus. Yes, you read that right—mold. But don’t panic. This isn’t the green fuzzy stuff on your forgotten bread. This mold forms a white, cake-like structure that binds the beans together, giving tempeh its signature texture and slightly nutty flavor.
The fermentation process not only makes the soybeans more digestible but also packs them with protein, probiotics, and nutrients. In short, tempeh is a nutritional powerhouse that also happens to be delicious.
What You’ll Need to Make Tempeh
First things first: gather your tools and ingredients. You don’t need a fancy kitchen or exotic equipment, but you do need a few basics:
Ingredients:
- Dried soybeans: Start with about 2 cups. Organic, non-GMO soybeans are ideal.
- Vinegar: 2 tablespoons (white vinegar or apple cider vinegar works fine).
- Tempeh starter: This is where the magic happens. You’ll need a teaspoon of tempeh starter, which you can buy online or at specialty food stores.
Equipment:
- Large bowl: For soaking the beans.
- Pot: To cook the beans.
- Colander: To drain and dry the beans.
- Mixing spoon: For stirring (obviously).
- Ziploc bags or banana leaves: To mold the tempeh. If you’re feeling traditional, banana leaves are great, but plastic bags work just fine.
- Needle or skewer: To poke tiny holes in the bag for airflow.
- Warm environment: Tempeh needs a steady temperature of around 85–90°F (30–32°C) to ferment. A warm oven, dehydrator, or even a DIY incubator with a heating pad can do the trick.
The Process, Step by Step
Making tempeh isn’t complicated, but it does require some patience and attention. Here’s your roadmap:
Step 1: Soak the Soybeans
Start by soaking the soybeans. Rinse them under cold water to remove any dirt or debris, then toss them into a large bowl and cover with water. The beans will swell as they soak, so make sure there’s plenty of water—at least three times the volume of the beans.
Leave them to soak for 12–24 hours. Longer is better because it softens the beans and starts breaking down some of the anti-nutrients that can make soy hard to digest.
Step 2: Dehull the Beans
This is the most tedious part of the process, so brace yourself. After soaking, you’ll need to remove the soybean hulls. The easiest way? Rub the beans between your hands in the water. The hulls will float to the surface, making it easy to skim them off. Yes, it’s a bit of a chore, but trust me, it’s worth it for the texture of the final tempeh.
If you’re short on patience, you can leave some hulls on—but too many can interfere with fermentation.
Step 3: Cook the Beans
Once the beans are dehulled, it’s time to cook them. Place the beans in a large pot, cover them with water, and bring to a boil. Reduce the heat and let them simmer for about 30 minutes until they’re tender but not mushy. You want the beans to hold their shape.
Drain the cooked beans in a colander and let them cool slightly. They should be warm, not hot, when you move to the next step.
Step 4: Dry the Beans
This step is crucial. Excess moisture can ruin the fermentation process, so the beans need to be as dry as possible. Spread them out on a clean towel or paper towel and pat them dry. Don’t skip this step unless you enjoy wasting hours on a moldy, soggy mess.
Step 5: Add Vinegar and Tempeh Starter
Once the beans are dry, transfer them to a mixing bowl. Add 2 tablespoons of vinegar and mix thoroughly. The vinegar helps create an acidic environment that’s perfect for fermentation.
Next, sprinkle the tempeh starter over the beans and mix well. You want an even coating, so take your time. The starter contains spores of Rhizopus oligosporus, which is what transforms your boring beans into glorious tempeh.
Step 6: Pack the Beans
Now it’s time to shape your tempeh. If you’re using Ziploc bags, fill each bag with a thin, even layer of beans—about 1–1.5 inches thick. Flatten the beans gently with your hands to make sure they’re packed tightly.
Use a needle or skewer to poke small holes all over the bag. This allows air to circulate, which is essential for fermentation. If you’re using banana leaves, wrap the beans tightly and secure with toothpicks or string.
Step 7: Ferment
Place your filled bags or wrapped leaves in a warm environment. The ideal temperature is around 85–90°F. If your house is chilly, you can use a dehydrator, an oven with the light on, or even a homemade incubator.
Let the tempeh ferment for 24–48 hours. You’ll know it’s ready when it’s covered in a firm white mold and has a faint, nutty aroma. If the mold is patchy or doesn’t form at all, it’s a sign something went wrong (probably temperature or moisture levels).
Tips for Success
- Keep it clean: Sterilize your equipment and work in a clean area. Contamination is the enemy of good fermentation.
- Check the temperature: A thermometer is your best friend. Too cold, and the mold won’t grow; too hot, and you’ll kill it.
- Don’t freak out: A little black or gray spotting on the mold is normal and harmless. But if you see green, toss it—it’s gone bad.
What to Do with Your Homemade Tempeh
Congratulations—you’ve made tempeh! Now what? Here are a few ideas to get you started:
- Slice and fry: Pan-fry tempeh slices until golden and crispy. Add soy sauce, garlic, or spices for extra flavor.
- Marinate and bake: Soak tempeh in a marinade of your choice (think soy sauce, maple syrup, and garlic), then bake it for a hearty, savory dish.
- Crumble into dishes: Tempeh works great as a ground meat substitute in tacos, stir-fries, or pasta sauces.
- Grill it: Brush tempeh with BBQ sauce and throw it on the grill for a smoky, charred treat.
Troubleshooting Common Problems When Making Tempeh
No matter how diligent you are, fermentation is a bit of an art. Sometimes things don’t go as planned, and that’s okay. If your tempeh doesn’t turn out the way you hoped, there’s usually a clear reason—and often an easy fix. Let’s go through the most common problems, their causes, and how to address them so your next batch is a success.
1. No Mold Growth
You’ve done everything right—or so you think. The beans are packed, the temperature is perfect, but 24–48 hours later, there’s no sign of that beautiful white mold. What’s going on?
Possible Causes:
- Temperature is too low: Rhizopus oligosporus thrives at 85–90°F (30–32°C). If your environment is cooler than this, the mold won’t grow.
- Starter wasn’t fresh: Tempeh starter contains live spores, which can lose their potency over time, especially if stored improperly.
- Too much moisture: Excess water can prevent mold from developing by creating a breeding ground for bad bacteria instead.
- Beans weren’t dried properly: If the beans were even slightly wet when mixed with the starter, it could create unfavorable conditions for fermentation.
Solutions:
- Check your temperature: Use a thermometer to ensure your incubation area stays consistently warm. If your home is cold, try placing the tempeh near a radiator, inside a turned-off oven with the light on, or using a heating pad.
- Use fresh starter: Always store tempeh starter in a cool, dry place or the fridge. If it’s been sitting around for months, buy a new batch.
- Dry the beans thoroughly: After boiling, pat the beans dry and let them air out before adding the starter.
- Be patient: Sometimes mold takes longer to appear, especially if conditions are slightly off. Give it another 12 hours before you give up.
2. Slimy or Wet Texture
Slimy tempeh is not just unpleasant—it’s a sign something went wrong. Tempeh should have a firm, cake-like texture. If yours feels gooey or wet, it’s usually because of one of the following reasons.
Possible Causes:
- Too much moisture: This is the most common culprit. If the beans were wet or the environment was humid, it can lead to a slimy mess instead of a firm mold cake.
- Contamination: Dirty equipment or hands can introduce bad bacteria, which thrive in moist environments.
- Fermentation stalled: If the temperature was too low or fluctuated too much, the fermentation process might not have progressed properly, leaving the beans vulnerable to bacterial growth.
Solutions:
- Control moisture: Make sure the beans are as dry as possible before packing them. A good rule of thumb is that they should feel barely damp—dry enough that they don’t leave water on your hands.
- Sterilize everything: Clean your bowls, spoons, and hands before handling the beans. This reduces the risk of contamination.
- Maintain a consistent temperature: Ensure your tempeh stays warm throughout the fermentation process. If your space is humid, consider using a fan or placing the tempeh in a dry area.
3. Black or Gray Spots
Don’t panic! Black or gray spots on tempeh are usually harmless. In fact, they’re a sign the fermentation process is moving along. However, if the spots look fuzzy or are accompanied by a foul smell, that’s a different story.
Possible Causes:
- Normal mold development: As Rhizopus matures, it can develop small black or gray spots. This is completely safe and common in older tempeh.
- Overfermentation: If the tempeh is left to ferment too long, the mold may become patchy and discolored.
- Contamination: In rare cases, black spots could indicate contamination, especially if they’re accompanied by green, yellow, or orange hues.
Solutions:
- Inspect the tempeh: If the spots are just small and black (like pepper), the tempeh is fine to eat. If they look fuzzy or colorful, toss it.
- Ferment for the right amount of time: Check your tempeh at the 24-hour mark. If it’s ready (firm and white), stop the fermentation by refrigerating it.
- Watch for smells: Safe tempeh should smell nutty or earthy, not sour or rotten.
4. Green, Yellow, or Orange Mold
This is where you draw the line. Green, yellow, or orange mold is not part of the plan. If you see this, it means your tempeh is contaminated and unsafe to eat.
Possible Causes:
- Poor sanitation: Contaminants from dirty tools, surfaces, or hands can outcompete the Rhizopus mold.
- Wrong temperature: If the tempeh was too hot or too cold, it might have encouraged harmful molds to grow instead of the good kind.
- Overly wet environment: High humidity or excess moisture in the beans can lead to contamination.
Solutions:
- Start fresh: Unfortunately, there’s no saving contaminated tempeh. Toss it out and begin a new batch.
- Sanitize everything: Wash and sterilize your tools and workspace thoroughly before starting again.
- Control moisture: Remember, dry beans are key to a successful fermentation process.
5. Sour or Rotten Smell
If your tempeh smells anything other than nutty or earthy, that’s a red flag. A sour, rotten, or overly strong odor indicates bacterial contamination.
Possible Causes:
- Beans weren’t acidic enough: The vinegar step is essential to create an acidic environment that discourages bad bacteria.
- Contamination: Poor hygiene or unclean equipment can introduce unwanted bacteria.
- Temperature issues: Fermentation at the wrong temperature can allow harmful bacteria to thrive.
Solutions:
- Always add vinegar: Don’t skip this step, and make sure to mix it evenly with the beans.
- Use clean tools: Wash everything thoroughly before starting your next batch.
- Monitor temperature: Keep the beans at a steady 85–90°F to encourage good mold growth and prevent bacterial takeover.
6. Tempeh Didn’t Bind
If your tempeh doesn’t form a firm, cake-like block and instead falls apart, it’s a sign that the fermentation process didn’t go as planned.
Possible Causes:
- Beans weren’t packed tightly enough: Loose packing leaves air gaps, which prevents the mold from binding the beans together.
- Starter wasn’t distributed evenly: Uneven mixing can result in patchy fermentation.
- Low temperature: If the environment wasn’t warm enough, the mold wouldn’t grow effectively.
Solutions:
- Pack the beans tightly: Press the beans firmly into the bag or wrap to ensure they’re compact. This helps the mold bind everything together.
- Mix the starter thoroughly: Make sure every bean is coated evenly with the starter.
- Use a warm space: Double-check your incubation area’s temperature and make adjustments if needed.
Final Thoughts on Troubleshooting Tempeh
Making tempeh can feel like a science experiment, and sometimes it takes a few tries to get it right. The key is to stay patient, pay attention to the details, and learn from your mistakes. Once you’ve mastered the process, you’ll be rewarded with fresh, delicious tempeh that’s better than anything you can buy in a store.
And remember—if at first you don’t succeed, don’t get discouraged. Tempeh-making is all about trial and error. With practice, you’ll figure out the quirks of your environment and develop a method that works for you.
Final Thoughts
Making tempeh might seem intimidating at first, but once you’ve done it, you’ll wonder why you didn’t try sooner. Sure, it takes some time and patience, but the payoff is worth it—a nutrient-packed, versatile protein that’s as good for your wallet as it is for your health.
So, get out there, embrace the mold, and start fermenting. Your homemade tempeh will blow the store-bought stuff out of the water. Just be warned: once your friends taste it, they’re going to expect you to make it for them, too.
