Combine ragi flour, rice flour, semolina, salt, and cumin seeds in a wide mixing bowl.

Pour in half the water and whisk until completely lump-free.

Add the remaining water gradually, mixing as you go, until you have a very thin, runny batter that flows easily off the ladle.

Stir in the chopped onion, green chili, ginger, curry leaves, and coriander.

Rest the batter for 15-20 minutes. The semolina absorbs the water and swells slightly, which helps create the lacy holes in the dosa.

Heat a cast iron tawa or non-stick dosa pan on medium-high flame until very hot. Test by sprinkling a few drops of water — they should sizzle and evaporate immediately.

Stir the batter well from the bottom before each dosa, as the flours settle quickly.

Pour a large ladle of batter onto the hot tawa from a slight height, moving in a wide circular motion from the edges inward. Do not go over the same spot twice — this creates the lacy, porous texture.

Drizzle 1 tsp of oil or ghee around the edges and over any dry patches.

Cook on medium-high for 3-4 minutes until the edges begin to lift from the pan and the surface looks dry and set.

Flip the dosa and cook for another 30-60 seconds on the other side, or skip the flip for a crispier single-sided dosa.

Fold in half, transfer to a plate, and serve immediately with coconut chutney or sambar.