In a bowl add the rice flour, all purpose flour and semolina and combine. Heat 2 tbsps of oil and add the hot oil to the flour. Carefully mix the oil into the flour mixture
Add the onion, green chili, curry leaves, coriander leaves, salt and asafoetida to the flour mixture.
Mix it well so that the onion releases some water. Set a side for 10 minutes.
After 10 minutes, mix it and add just enough water to form a slightly firm dough.
Grease your hand with oil and take a portion of the dough and form a ball. Place the ball on a greased banana leaf or parchment paper and gently flatten it.
Heat oil in a kadai and adjust the knob to medium flame. To check if the oil is at the right temperature, drop tiny amount of dough in to the hot oil. If the dough comes up slowly, the oil is ready to be fried.
Slowly drop the flattened dough into the hot oil and fry on both sides in medium flame till golden brown. Do not rush, frying in medium flame helps in getting crispy vada