Roughly chop the tomatoes and green chilies, then blend them together in a blender or food processor until smooth to make the tomato-chili puree used in step 5. ( Don't have a blender? Grate the tomatoes on a box grater and finely mince the chilies by hand instead.)
Heat oil in a pan over medium heat. Add the chopped onion and sauté until softened and lightly golden.
Add the ginger paste and garlic paste, and cook until the raw smell disappears.
Stir in the salt, Kashmiri chili powder, ground cumin, ground coriander, and turmeric. Add a splash of water if needed so the spices don't burn.
Add the pureed tomatoes and chilies from step 1. Cook on medium heat until the oil separates from the masala, adding a splash of water if needed.
Add the boiled kala chana (see How to Boil Kala Chana for instructions) along with some water to reach your desired consistency.
Cover and cook on low heat for 8–10 minutes, checking and stirring in between.
Serve hot with puri, paratha, roti, or kachumber.
Notes
Soak the chana fully and cook it until soft. Undercooked chana won't let the curry thicken properly.
A spoon of ghee stirred in at the end adds richness. Skip it if you are keeping it strictly vegan.