For the dosa batter: Soak urad dal in water for 8 to 12 hours. Wash the soaked lentils and blend in a high-powered blender with 3/4 cup water to a smooth paste. Add rice flour, sugar, salt and 1 1/2 cups water to blend to a smooth paste consistency. Let batter ferment at room temperature 8 to 10 hours.
For the onion masala: Heat the rice bran oil in big saute pan until hot, then add cashews, chana dal, mustard seeds, turmeric powder, red chiles, curry leaves and onions and cook, stirring constantly, over medium heat, until caramelized, about 30 minutes.
Potato masala and tempering: Heat oil in a saute pan until hot, then add mustard seeds. Cook until you hear the crackle, then add cilantro, asafoetida, chiles, potatoes, curry leaves, salt and 1 1/2 cups onion masala.
For the coconut chutney: Add coconut, chana dal, coconut powder, chiles, tamarind seeds, cilantro and salt to a high-powdered blender with water and blend to a smooth paste consistency. Finish by adding a tablespoon of tempering to the coconut chutney.
Heat a cast-iron or nonstick pan over medium heat and season with oil. Once it is hot, take one ladle of dosa batter and spread it from the middle to outer edge of the pan, making sure it is thin. Cook until cooked completely, about 1 minute. Put ghee on top of dosa. Serve with potato masala and coconut chutney. Repeat with remaining batter.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.