In a large bowl combine chick peas, tomatoes and tomato paste. Set aside. In a large pan heat the oil over moderately-high heat. Add the onion, garlic, ginger, cumin and coriander. Cook, stirring often, until the onions turn light brown, about 8 minutes. Add zucchini, bell peppers and salt and black pepper to taste. Pan roast the vegetables, stirring regularly, for 5 minutes.
Add chick pea-tomato mixture to the onion mixture. Add water and bring contents to a boil. Lower heat and simmer, covered, for 5 minutes, or until the flavors are blended and the sauce is very thick. Serve ragout topped with yogurt.
For the topping: Combine yogurt, cucumber, scallion, coriander and hot green chilies.
c. Julie Sahni 1998. Adapted from Julie Sahni's Introduction to Indian Cooking,Ten Speed Press 1998. Used with permission