Heat oil in a non-stick pan. Add Slice onion, Chopped capsicum, add tomatoes saute well until it is cooked well.
Add turmeric powder, tomato puree, ginger-garlic paste, garam masala, chilli powder and salt. Mix well and cook till done.
Mix mint-coriander chutney and yogurt and enough salt in a small bowl.
Spread a spoonful of yogurt-chutney evenly on chapatti. Place a spoonful of the vegetable filling on one side of the chapatti. Roll the chapatti tightly.
Make other kathi rolls similarly. Cut into halves and serve immediately.