The objective of fermenting beans is to make them more digestible, unlock their nutrient potential, and give the beans compelling flavors, as well as pleasing textures. For example, soybeans, though renowned for their protein richness, are mostly indigestible by human digestive tracts when raw or unfermented. In this state, we can’t fully absorb their essential amino acids because they’re blocked by rigid cellulose compounds. Fermentation, however, predigests the beans, breaking down the proteins into individual amino acids that we can more easily absorb, while simultaneously breaking down the nutrient-blocking compounds. Fermentation is the most effective way to realize the powerful nutritive potential of legumes, especially soybeans. In addition, when legumes are fermented together with grains, the ferment becomes a complete protein, containing all of the amino acids essential to human nutrition.
Documentation of bean fermentation goes back thousands of years. Ancient Chinese texts refer to “jiangs” — condiments fermented from beans — as well as to fish, meat, grains, and vegetables. Jiangs come in an elaborate variety and are deeply imbued with meaning. The Analects of Confucius from 500 B.C. instructs readers that “foods not accompanied by the appropriate variety of jiang should not be served. Rather than using only one to season all foods, you should provide many to ensure harmony with each of the basic food types.”
Most bean ferments start just as grain ferments do: by adding water to bring the seed back to life, swelling and awakening dormant microbial and enzymatic activity.
Making a Basic Batter
Dosas and idlis are primarily South Indian foods, made from fermented batter. Dosas are thin pancakes, while idlis are steamed breads, both created from batters born of the same rice-and-lentil ferment, which only takes a day or two to make. The two foods share a wonderful flavor, but boast very different textures. Some compare idlis with matzo balls, but I think they have a distinctive, spongy texture all their own. Dosas and idlis are the easiest, fastest, and most straightforward of the bean ferments.
Yield: about 6 cups of batter, enough for about 32 dosas or idlis.
Fermentation type: Lacto
Primary Fermentation: 8 to 24 hours
Total Time: 1 day
- 2 cups white, brown, or parboiled rice
- 1/2 cup white or red lentils (known respectively as urad dal or masoor dal in Hindi)
- 1 teaspoon fenugreek seeds
- 1 teaspoon salt
- In a large bowl, rinse the rice until the water drains clear, then cover with water and soak for at least 8 hours.
- In a separate bowl, rinse the lentils. Add the fenugreek seeds, and cover with water. Use twice the volume of water as the volume of the lentils, because the lentils will double in size. Soak for at least 8 hours.
- Drain the lentils and fenugreek seeds, saving the soaking water in a separate bowl. Grind the lentils and fenugreek seeds into a batter, using either a grinder or a blender. Grind for a few minutes, until the batter is smooth. Add the soaking water as needed, but use as little as possible. Scoop the mixture out of the blender and into a clean mixing bowl.
- Drain the rice, saving the soaking water in a separate bowl. Grind the rice, in batches if necessary. Add soaking water, but use as little as possible. Grind into a smooth paste, and then add it to the ground lentils and fenugreek.
- Add the salt, and beat the two batters together into one.
- Add the batter to a fermentation jar, leaving plenty of room for it to expand. Allow to ferment for 8 to 24 hours, or even longer in a cool environment, until it has roughly doubled. Once it rises, use the batter to make dosas and/or idlis, or refrigerate up to a month for later use.
Want to learn more about making Dosas and Idlis? Check out these recipes:
Sandor Katz is a fermentation revivalist. A self-taught experimentalist, his explorations in fermentation developed out of overlapping interests in cooking, nutrition, and gardening. Wild Fermentation (2003), The Art of Fermentation (2012), and the hundreds of fermentation workshops he has taught around the world have all helped to catalyze a broad revival of the fermentation arts.
This is an excerpt from Sandor Katz’s book Wild Fermentation: The Flavor, Nutrition, and Craft of Live-Cultured Foods, 2nd Edition (Chelsea Green Publishing, August 2016), and is reprinted with permission from the publisher.