Tempeh is the Indonesian soybean cake made by fermenting soybeans with Rhizopus mold.
Tempeh originated on Java, where whole soybeans are soaked, dehulled, partially cooked, cooled, and inoculated with a starter culture. Rhizopus species, especially Rhizopus oligosporus and Rhizopus oryzae, grow through the beans as white mycelium, binding them into a firm cake over roughly 24 to 48 hours under suitable conditions.
Unlike tofu, which is made by coagulating soy milk, tempeh retains the whole soybean. That gives it a dense, sliceable texture and a nutty, earthy flavor. Fermentation also changes the beans’ digestibility and reduces some of the oligosaccharides associated with digestive discomfort.
Natto is another fermented soybean food, but it uses different microbes and has a notably sticky texture. Miso is a fermented soybean paste, while tofu is not fermented at all. Tempeh can be fried, steamed, baked, crumbled, or marinated, making it both a traditional Indonesian staple and a widely used meat alternative.