Heat oil in a pan. When it is hot, add mustard seeds. When mustard starts to splutter add uradh dhal, cumin seeds and when urad dhal turns golden brown, add green chilli. Fry it for about 20 seconds.
Now add tomatoes. Fry it till tomatoes get cooked. Do not add water. Let tomatoes cook on its own.
Once tomatoes are cooked, transfer it in a serving bowl and add1/2 cup yogurt. You can add water to dilute the yogurt as required. Add salt and mix well.
Tomato raitha is ready to be served with hot pulao or carrot rice or any other curried rice. Tastes really good. It is different from the regular raitha as we first sautee the tomatoes. This gives a different taste to the dish.