Take oil in a pan. Add mustard seeds, red chillies. After it splitters, slide cut onions into the pan and fry them until light brown in colour. Add chopped tomatoes and fry for 2 minutes followed by capsicum.
Now add jeera powder, jaggery, salt, coriander powder with 1/2 cup water.
Stir everything and close the lid and cook for 10 minutes.
Keep stirring in between and add little water if needed. This curry goes very well with rice or chapatti.