Fry red chillies in oil till they change color and set them aside (they will be used later)

In the same oil, add sliced shallots/onions, green chilli, curry leaves, ginger-garlic paste. Add salt

Fry till onion turns slightly brown and then add tomatoes

Continue to saute this until the tomatoes become soft

Take all the fried ingredients along with fried red chili, add a bit of water and blend to a pulp

Tempering
Add mustard seeds to hot oil
Add curry leaves
Add pinch of hing
Add the blended pulp

Saute till it becomes thick and the color changes to become darker