It might look unappetizing but this is what you want: very fuzzy with large blooms of dark-gray.
Tempeh is created by fermenting certain grains or legumes with Tempeh Starter (a mold called Rhyzopus Oryzae). Once you’ve made tempeh, you can easily grow more of the mold. You can do it in your oven with just the oven light turned on.
Grow Your Own: Tempeh Starter
It's best to do this immediately after making some tempeh, while the tempeh and oven are still warm. You can reheat cold tempeh in the oven with the light on, but be sure to cover it with a towel so it doesn't bloom too soon.
Equipment
- oven with light
- baking pan
- plastic wrap
- bowl of water
Instructions
- Turn on the oven light and put a small bowl of water on the floor of the oven.
- Cut off a few 1-inch-square chunks of fresh tempeh and put them in a baking pan. Leave some room around each chunk.
- Cover the baking pan with plastic wrap. Poke a few holes in the plastic wrap for air circulation.
- Put the baking pan in the oven, as close to the light as possible. Light, warmth, and humidity are needed to make the mold bloom.
- Leave to incubate about 30-36 hours. Check occasionally to make sure growth is happening. At first you'll see long threads of pale gray fuzz. As the mold blooms it will develop large areas of dark gray to black. Do not use if any other color appears.
- When you are satisfied with the bloom, remove the bowl of water and take the plastic off the baking pan. Break the tempeh into smaller pieces so it can dry faster.
- Return the baking pan to the oven, with the light still on, and allow it to dry for another day or so. It should be dry as a cracker and should snap when you break it.
- Grind the tempeh starter into a fine powder. Store in an air-tight container at room temperature for up to 6 months.