Tempeh

Soak the soybeans in enough water to cover by an inch for at least 6 hours.

Remove the hulls of the soybeans by agitating the beans and skimming the floating skins away. Not all skins need to be removed, but the majority of the beans should be liberated so that the fungus can properly culture.

Transfer the beans to a pot of water. Bring to a boil, then reduce heat and simmer until al dente, about 40 minutes. Take care not to over cook the beans or they will be too soft to work with. The beans should be soft, but still firm enough to hold their shape.

Drain and spread beans evenly over a flat surface and let stand until mostly dry.

Transfer beans to a large container along with the starter and vinegar. Gently toss to evenly distribute starter throughout the beans.

Transfer mixture to a covered, but not seal container. The beans should have air circulation, but not so much that they dry out. A shallow, flat dish is best for this, as it gives the tempeh a more convenient shape. {Editor's note: Does the surface area matter?}

Place covered container in a location kept at a stable 88.F. Let ferment until covered in a white fuzz, 1-2 days. Grey spots indicate the beginning of sporulation, which does not harm the final product.