Firstly, in a bowl, add 1 cup besan, ½ tsp salt, ½ tsp red chilli powder, 3-4 tbsp water, and whisk everything well.
Set the consistency of the batter and make it lump-free.
Set a dosa tawa over a high flame and let it get extremely hot. Sprinkle some water and clean it properly.
Pour the batter using a ladle by giving it a round shape. After pouring, immediately set the flame to medium.
Spread chopped onion, tomato, and grated paneer on the half side. Sprinkle sambhar masala over it.
As it turns brown, start removing it from the sides.
Fold it and remove from the tawa. Similarly, prepare the other one.
Finally, enjoy besan chilla with tomato ketchup.