Firstly, in a large bowl take 2 cups raw rice and ½ tsp methi. Rinse well and soak in water for 4 hours.
After 4 hours, drain off the water and transfer to the mixi along with aval and grated coconut.
Blend to a smooth paste adding water as required. Transfer the rice batter to a large bowl. Cover and allow to ferment in a warm place for 8 hours.
After 8 hours, the batter has well fermented. Now to prepare the tempering, heat 3 tsp oil, splutter 1 tsp mustard seeds,1 chopped chilli and few curry leaves. Pour the tempering over the batter and mix well. Also, add 1 tsp salt and give a good mix.
Now heat a Appam pan and grease it with oil. Pour a ladle full of batter into the pan. Cover and simmer for 3 minutes. Make sure not to spread the batter. Once the base turns golden brown, flip over the dosa. Cook on both sides making sure the dosa is cooked uniformly.
Finally, enjoy Bun Dosa with coconut chutney.