A dosa is a gluten-free, protein-rich dish that is eaten throughout the day in India.
1. Two or three days before serving, in a large bowl combine rice, urad dahl, and fenugreek seeds, if using. Add enough water to cover by 2 to 3 inches. Let soak, uncovered, at room temperature until dahl and rice are soft enough to break apart easily, at least 8 hours.
2. Drain rice and dahl in a fine strainer. In a blender, whirl the rice mixture, warm water, and salt until smoothly blended. If needed, stir in a little more water to make a thin batter. Pour into a large bowl. Cover and let stand in a warm place (75° to 85°F) until batter is bubbly and almost doubled in volume, anywhere from 12 to 24 hours. The batter should coat a spoon in a medium-thick layer and resemble a thin, airy pancake batter.
3. Near the stove, set a small bowl of oil with a brush, a bowl of water, and a paper towel. Set a griddle or 12-inch frying pan with a heavy, flat bottom over medium-high heat. Lightly coat it with oil. With the folded paper towel, spread the oil evenly over the surface and wipe off the excess.
4. Pour about 1/3 cup batter into a flat-bottom measuring cup. When the griddle is hot, sprinkle a few drops of water over it with your fingers; the water should sizzle immediately. Pour the measured batter into the center of the griddle or pan. At once, with the bottom of the measuring cup, quickly spread the batter from the center in even concentric circles to make a thin, even crepe that is about 8 inches in diameter.
5. With a brush, drizzle a few drops of oil around the edges of the dosa. Cook until the bottom is golden brown and the edges begin to curl, about 2 minutes. With a wide spatula, loosen the edges. (It isn’t necessary to brown both sides, but if the dosa is on the thick side, you can flip it and cook the other side until golden, about 30 seconds.)
6. Mound a large spoonful of potato masala on one side of the dosa. Fold the other side over the potatoes, then slide the dosa onto a dinner plate. After making each dosa, wipe the griddle clean with the paper towel. It is not necessary to oil the griddle after each dosa unless it begins to stick. Repeat to make remaining dosas. (If the batter was too thick to spread easily with the first dosa, stir in a little water to thin the batter slightly before making the next one.)
Note: The time it takes for the batter to ferment will depend on how warm your kitchen is. Once the batter has fermented, you can hold it in the refrigerator for a day or two. Bring it to room temperature before using.
Recipe by Linda Lau Anusasananan, former food writer and recipe editor at Sunset magazine and author of The Hakka Cookbook: Chinese Soul Food From Around the World.