In a large stock pot or skillet add the oil and sauté the onions until almost golden.
Next add the garlic, ginger paste, chiles, chana masala (optional), cumin, turmeric, garam masala and salt. Stirring to mix thoroughly.
Add diced tomatoes and chickpeas (reserve 1 can chickpea liquid) to the onions. Slowly simmer for 30 minutes, uncovered.
Add the mango powder (optional), lemon juice and stir to incorporate completely. Season to taste. If the mixture is too thick feel free to dilute with water or chickpea liquid.
Serve with garnish of chopped cilantro and lemon wedges.
Video
Notes
If using fresh Roma tomatoes: removing the skins is optional. To remove tomato skins, cut a small X on the opposite end of the stem side, then cook the tomato in boiling water for 3 minutes. Remove and place into a large bowl of ice water to stop the cooking. Using a paring knife peel back the skin from the X cut, discard the skins and dice the tomatoes.
If you choose to use dried chickpeas instead of canned, follow the instructions in my post, how to cook chickpeas.
Lemon juice may be substituted for amchur, the sweet and sour mango powder, if unavailable. Substitute three tablespoons of lemon juice for one teaspoon of amchur. May also substitute 1 tablespoon pomegranate molasses as well.