preserve · Preserve

How to Make Tempeh from Scratch

Making tempeh requires soaking and dehulling soybeans, inoculating them with tempeh starter, then fermenting in a warm environment for 24-48 hours until white mycelium binds the beans into a solid cake. The process takes three days from start to finish but only requires active work on the first day.

Total time: 32 hr 45 min
Hands-on: 1 hr
Difficulty: Hard

Ingredients

2 cups dried soybeans
2 tbsp white vinegar
1 tsp tempeh starter (Rhizopus oligosporus spores)

Step by step

Soak the soybeans. Place 2 cups dried soybeans in a large bowl with enough water to cover by 3 inches. Soak for 8-12 hours until the beans double in size and the skins start to loosen.
Dehull the beans. Drain the beans and rub them vigorously between your hands under running water. The loosened hulls will float to the surface. Continue rubbing and rinsing until you've removed at least 90% of the hulls. This step is crucial for proper fermentation.
Split and cook the beans. Break each bean in half by squeezing gently. Boil the split beans in plenty of water for 45-60 minutes until tender but still firm. They should hold their shape when stirred.
Dry the beans completely. Drain the beans and spread them on clean kitchen towels. Pat dry and let them air dry for 30 minutes. The beans must be completely dry before adding the starter or the tempeh will spoil.
Add acid and starter. Sprinkle 2 tablespoons white vinegar over the beans and mix thoroughly. Add 1 teaspoon tempeh starter (Rhizopus oligosporus spores) and mix until every bean is coated with the white powder.
Pack into containers. Place the inoculated beans in perforated containers - either banana leaves, plastic bags poked with holes every inch, or shallow pans covered with perforated plastic wrap. The beans should be 1-2 inches thick maximum.
Ferment at proper temperature. Keep the tempeh at 86-88°F for 24-48 hours. Use a dehydrator, oven with light on, or heating pad. White fuzzy mycelium will grow and bind the beans together. Stop when the entire surface is white and the tempeh holds together as one piece.

Tips & troubleshooting

Temperature consistency matters more than exact temperature. Fluctuations will slow or stop fermentation.
The vinegar creates the acidic environment the tempeh mold needs while preventing harmful bacteria growth.
Fresh tempeh smells nutty and earthy. Any ammonia smell means it's over-fermented but still safe to eat if cooked thoroughly.
Dehulling is tedious but essential. Hulls prevent the mycelium from binding the beans properly.
Store finished tempeh in the refrigerator for up to a week or freeze for up to three months.

Variations

Black Bean Tempeh. Replace soybeans with black turtle beans. Follow the same process but cook the beans 15 minutes longer as they're denser than soybeans.
Mixed Grain Tempeh. Combine cooked soybeans with cooked barley, rice, or millet in equal parts. The grains add texture and different flavors to the finished tempeh.
Banana Leaf Wrapped. Traditional Indonesian method using banana leaves instead of plastic. Blanch leaves briefly, wrap the inoculated beans, and secure with toothpicks.

Questions

Where do I find tempeh starter?: Order tempeh starter online from fermentation supply companies or Asian grocery stores. Store unopened starter in the freezer where it lasts for years.
What if black spots appear during fermentation?: Small black spots are normal - they're the spores of mature tempeh mold. Large black patches or any colored mold other than white means something went wrong and you should discard the batch.
Can I make tempeh without a temperature-controlled environment?: In warm climates, tempeh will ferment at room temperature, though it takes longer and results are less predictable. In cooler areas, you need some form of gentle heat to maintain the proper temperature range.
How do I know when tempeh is ready?: The entire surface should be covered in white fuzzy mold and the tempeh should hold together as one solid piece when lifted. It typically takes 36-48 hours in optimal conditions.