Dosa Batter

Rinse the rice and urad dal separately in several changes of cold water until it runs clear. Combine the urad dal and fenugreek seeds in one bowl and the rice in a separate bowl. Cover each generously with cool, non-chlorinated water and soak for 6 to 8 hours, or overnight. They must be soaked separately because the dal grinds to a different consistency than the rice and requires a different texture grind. Keep in a cool place but not the refrigerator — the ambient bacteria on the grains are the fermentation agents and cold temperatures suppress their activity.

Drain the urad dal and fenugreek seeds, reserving their soaking water. In a high-powered blender, grind the dal with fenugreek using a minimal amount of the reserved soaking water — just enough to get the blender moving. The urad dal must be ground ultra-fine, to a smooth, aerated foam-like paste that is almost sticky, roughly 5 to 8 minutes of grinding. It should feel like thick, dense foam. Separately, drain the rice and grind it with more reserved water to a slightly coarser, granular paste — some very fine grains are acceptable and help give the dosa texture. Combine both in a large container with room to rise: the batter will increase in volume by 30 to 50% during fermentation.

Cover the combined batter loosely — a plate or cloth, not an airtight lid — and place in a warm spot at 28–32°C (82–90°F). In a North American or European kitchen in winter this may mean a turned-off oven with only the light bulb on, or near a radiator. Ferment for 8 to 12 hours. The batter is ready when it has risen noticeably, smells faintly sour, and the surface is bubbly and porous-looking. Add salt only after fermentation is complete — salt added before fermentation suppresses the wild yeast and bacteria. Stir the salt in gently, trying not to deflate the risen batter unnecessarily.

Heat a cast-iron or heavy non-stick skillet over high heat until it begins to smoke lightly. Rub the surface with a cut onion half dipped in oil — this seasons the pan and prevents sticking. Ladle approximately 80ml of fermented batter into the centre of the hot pan. Immediately and confidently use the back of the ladle in a circular motion to spread the batter outward from the centre in a single continuous spiral — you have about 10 seconds before it sets. Drizzle a few drops of oil around the edges. Cook on high heat until the edges lift and curl away from the pan and the underside is deep golden-brown and crisp, about 2 to 3 minutes. Flip only if you want a double-cooked dosa — the traditional paper dosa is cooked on one side only.