Heat oil and add mustard seeds. Once it completes spluttering add onion into it.

Add the chopped onions and saute till they are softened then add chopped green chilly and curry leaves.

After sometime when it cooks add tomatoes. Stir and saute till the tomatoes have softened and cooked. Ensure that no raw aroma is left.

Then add chilly powder, turmeric powder and salt. Cook it for a minute. Then keep side.let the chutney mixture become cool. later add in a chutney grinder or a blender jar. You can grind it without adding water or if you are preferring even smooth consistency then add a tbsp water.