Wash and rinse the rice and soak the rice and methi seeds in buttermilk until the rice is completely immersed. Add more water if needed to completely soak the rice. Let it soak for 3-4 hours.
Drain the rice and reserve the liquid. Using this reserved liquid, grind the rice and methi seeds along with the coconut and cooked rice to a thick and fine paste. Let this mixture ferment for 5-6 hours.(Note: if you accidentally added too much liquid, add tablespoons of rice flour at a time to thicken the batter)
Heat a heavy bottomed pan for 2-3 minutes on medium to low heat. Grease it with clarified butter.
Using a ladle to scoop the batter and pour it into the pan. Cover the pan and let the dosas cook for 3-4 minutes. Uncover the pan. At this point, bubbles would have started to form and pop.
Flip the dosas on the other side and cook for a minute or two. (Note: if you notice that the dosa is not soft and spongy, add 1/2 teaspoon of baking soda to the batter and mix well).