Heat oil in a saute pan; add the onions, ginger, garlic and red chilies. Cook till onions are lightly browned.
Add the cooked veggies, mix well. Cover and cook till the veggies are cooked through.
Add the chopped tomatoes, ground cumin, turmeric, red chili powder and salt. Cook covered till tomatoes turn mushy.
Finally add the garam masala, mix well and turn off the heat. Serve hot with rice or roti.