Grind the coconut, yogurt, and cumin seeds into a fine paste.
In a pan add 3 tsp coconut oil and add the mustard seeds, slit green chili, red chili, and curry leaves.
Add the sliced onions to this and cook till translucent.
Add finely chopped tomatoes.
Now add salt and turmeric powder.
Cook till the tomatoes are mushy.
Now add the ground yogurt mixture.
Add ½ cup of water to this.
Mix well and let this froth up.
Switch off the flame.
Tomato yogurt curry is ready to serve.
Serve with plain rice or idiyappam or sevai.