Khatte Chhole (sour chickpeas)

From Indian Cooking by Madhur Jaffrey

12 oz. dried chickpeas, picked over and rinsed
3 pints water
10-11 oz. onions, finely chopped
2 1/2 tsp salt
1 hot green chile, finely chopped
1 Tbsp fresh ginger, very finely grated
4 Tbsp lemon juice
3-6 Tbsp vegetable oil
8 oz. tomatoes, finely chopped (or a drained 15-oz. can of chopped tomatoes)
1 Tbsp ground coriander
1 Tbsp ground cumin
1/2 tsp ground turmeric
2 tsp garam masala
1/4-1/2 tsp cayenne pepper

Soak the chickpeas overnight. Pour the beans and their soaking liquid into a large pan and bring to a boil. Cover, lower the heat and simmer gently for 1 1/2 hours or until the chickpeas are tender. Strain the chickpeas and save the cooking liquid.

Put 2 tablespoons of the chopped onions, 1/2 teaspoon of the salt, the green chile, ginger, and the lemon juice into a teacup. Mix well and set aside.

Put the oil in a heavy, wide, casserole-type pan and set over medium-high heat. Once hot, add the remaining chopped onions. Stir and fry for 8-10 minutes, or until the onions bits develop reddish-0brown spots. Add the tomatoes. Continue to stir and fry for another 5-6 minutes, mashing the tomato pieces with the back of a wooden spoon. Add the coriander, cumin, and turmeric. Stir and cook for about 30 seconds. Next, add the drained chickpeas along with 14 fluid ounces of their cooking liquid, plus the garam masala, cayenne pepper, and 2 teaspoons of salt. Stir to combine and bring to a simmer. Cover, turn heat to low, and cook very gently for 20 minutes, stirring every 5 minutes. Add the mixture in the teacup. Stir to combine, and serve. (Good with rice.)