Tempeh is a fermented food traditionally made from soybeans. It originated in the islands of Indonesia and is a staple of the Indonsian diet today. Tempeh has become popular in other parts of the world because of its impressive nutritional composition, desirable firm texture, and earthy flavor. It is very easy to cook and is a perfect substitute for meat in a vegetarian diet.
How it's made
Soybeans (or other legumes) are split and boiled. The beans are then dried and inoculated with spores of the culture Rhizopus oligosporus, which is the main active ingredient of the tempeh-making process (think of it as the yeast you'd add while baking bread). The inoculated beans are then incubated at around 88 degrees F for about 30 hours, or until the tempeh has become a dense white "cake."
After the tempeh has been removed from incubation, it is frozen to preserve its active enzymes and freshness.