Idli with Coconut Chutney

To prepare idli: Place idli rice in a colander and rinse with cold water. Transfer to a large bowl and generously cover with filtered water. Place urad gota in the colander and rinse with cold water. Transfer to a medium bowl and add fenugreek seeds; generously cover with filtered water. Put both bowls in a warm place (the oven with the light on works well) and leave to soak for at least 6 hours and up to overnight.

Drain the rice and lentils, reserving 1 cup of the soaking liquid from the lentils. Process the lentils and 1/4 cup reserved soaking water in a high-speed blender until smooth, adding more water if needed. The batter should be fairly thick. Transfer to a large bowl. Repeat this process with the soaked rice, cooked rice and 1/4 cup soaking water. Add more water, if needed, to create a smooth, fairly thick batter with a slight grittiness. Transfer to the bowl with the lentil batter.

Use your hands to combine the lentil and rice batters. Cover the bowl with a damp kitchen towel and leave to ferment in a warm place for 8 to 24 hours, depending on temperature and humidity. The batter is ready when it has doubled in size, is a bit bubbly and has a tangy smell. (Check it by seeing if 1 teaspoon batter floats in a cup of tap water; if it does, it's ready.)

Stir 2 teaspoons salt into the batter. The batter should be thick and fluffy but pourable, like a thick smoothie. Add water in tablespoon increments, if needed.

Add 2 inches of water to a large pot; bring to a boil. Coat the plates of an idli stand with cooking spray. Fill each depression with a scant 3 tablespoons batter. Stack the idli plates on the stand and transfer to the pot. Cover and steam over medium heat until firm, about 12 minutes. Remove the stand from the pot and let cool for 4 minutes. Unmold the idli using a wet spoon. Repeat with the remaining batter. (Alternatively, if you don't have an idli stand, use a rimmed metal pan in your steamer; fill the pan half-full of batter. Cut the resulting large idli into wedges to serve.)

To prepare chutney: Place coconut, green chiles, ginger, cilantro, yogurt, 1/4 cup water, lemon juice and salt in a blender. Process until smooth. Transfer to a medium bowl.

Heat oil in a small saucepan over medium heat. Add mustard seeds and urad dal; cook, partially covered, until the seeds stop popping and the dal turns reddish brown, about 1 minute. Remove from heat and stir in whole red chiles and curry leaves to taste. Pour the hot mixture over the chutney. Serve the idli warm or at room temperature with the chutney on the side.