Pressure cook the chickpeas with enough water and salt. After it is cooked, take about 1/4 cup boiled chickpeas and mash to a smooth paste.
Heat 5 tablespoon cooking oil in a saucepan. Fry chopped onion till light brown and then add chopped tomatoes. Cook till the tomatoes start to wilt and then add the ground masala paste, 2 teaspoon coriander powder, 1 teaspoon cumin powder, and 1/4 teaspoon turmeric powder. Stir and cook on low heat for 5 minutes or until the raw smell disappears and oil starts to separate.
Now add boiled chickpeas and 1 cup of water from the cooker (add more water only if needed).
Stir well and add coconut milk, mashed chickpeas, 1/4 teaspoon garam masala powder, tamarind pulp, and salt if needed. Place the lid and cook on low flame for 10 minutes.