Hm. In response to a conversation with jessicapierce
I thought it might be useful to node some more detailed information on tempeh.
So what is it? Tempeh is a pressed cake made from soy beans and/or grains that has been a staple in Indonesia for centuries.
It is made by hulling and cooking the beans and grains and then inoculating them with a culture called rhizopus oligosporus. The stuff is then incubated overnight. In the tropics, this might not need many special circumstances. If you are doing this at home make sure it is kept at a temperature of 88 Degrees Fahrenheit. The beans or grains will become covered with a thick, white mat of mycelia binding them together into a solid cake.
It can be eaten the next day or refrigerated for about a week. As it ages it will develop unsightly black spots. These are not harmful.
Unlike other soy foods such as tofu, tempeh should not be eaten uncooked.