Mix rice flour, semolina, and all-purpose flour in a bowl.
Add water, salt, cumin, green chilies, and whisk into thin batter.
Heat a nonstick pan, grease lightly, and pour the batter thinly.
Sprinkle finely chopped onions, cilantro, and green chilies over the dosa.
Cook on medium flame until edges turn golden and crisp.
Gently loosen, fold the dosa, and remove from the pan carefully.
Serve hot with coconut chutney or spicy sambhar for dipping.