Prepare the Chickpeas:

1. Soak: Rinse the dried chickpeas and soak them in plenty of water overnight or for at least 8 hours. Drain and rinse.
2. Cook: In a large pot or pressure cooker, cook the soaked chickpeas in fresh water until tender. This can take 45-60 minutes on the stovetop or 15-20 minutes in a pressure cooker. Once cooked, drain the chickpeas and set aside.

Cook the Masala:

1. Sauté Aromatics: Heat the vegetable oil in a large pan over medium heat. Add the cumin seeds and let them sizzle for a few seconds. Add the chopped onion and cook until golden brown, about 7-10 minutes. Stir in the minced garlic and ginger, and cook for another 2 minutes.
2. Add Tomatoes and Spices: Add the chopped tomatoes and green chilies. Cook until the tomatoes break down and become a thick paste, about 10 minutes. Stir in ground coriander, ground cumin, turmeric powder, garam masala, and chili powder. Cook for another 2-3 minutes.
3. Combine Chickpeas: Add the cooked chickpeas to the pan. Stir well to coat them with the tomato and spice mixture. Pour in the coconut milk (if using) or a little water to achieve desired consistency. Simmer for 10-15 minutes to let the flavors meld.
4. Finish: Stir in the amchur (or lemon juice), salt, and black pepper. Adjust seasoning to taste. Simmer for an additional 5 minutes.

Serve:

1. Garnish: Garnish with fresh chopped cilantro.
2. Accompaniments: Serve hot with basmati rice or Indian bread (naan or chapati)