Ingredients

1. 1/2 cup split urad dhal (3 1/2 ounces)
2. 2 cups warm water
3. 1/4 teaspoon active dry yeast
4. 1 cup rice flour
5. 1/2 teaspoon salt
6. 1/2 cup plain yogurt
7. 1 tablespoon vegetable oil
8. 1 tablespoon Asian sesame oil

Directions

1. Rinse the urad dhal in several changes of water, then soak it for 4 hours; drain.
2. In a food processor, combine the dhal with 1/2 cup of the water and pulse until finely ground. 
3. In a large bowl, mix the yeast with 2 tablespoons of the water and let stand until foamy, about 10 minutes. Add the ground dhal, rice flour, salt and 3/4 cup of the water and whisk until a smooth, thick batter forms. Cover loosely with plastic wrap and let stand in a warm place until foamy and doubled in bulk, 12 to 18 hours. Add the yogurt and the remaining 1/2 cup plus 2 tablespoons of water to make a pourable batter. 
4. In a small bowl, combine the vegetable and sesame oils. Heat a 10-inch cast-iron skillet over moderately low heat. Dip a paper towel in the oil and carefully wipe the inside of the skillet. Using a ladle, stir the batter and pour1/4 cup into the center of the skillet. Working quickly, spread the batter out evenly to make an 8-inch pancake; move the back of the ladle in a spiral motion from the center. Fill in any large holes with a little extra batter. When the top looks dry and the underside has browned, about 1 minute, turn the dosa and cook until lightly browned, about 30 seconds. Transfer to a platter and continue making dosas, wiping the skillet with oil each time. Serve as soon as possible.

Make Ahead

The recipe can be prepared through Step 3 and refrigerated, covered,for up to 2 days.

Serve With

Red Coconut Chutney and Kerala Sambar