Wash the chickpeas 2-3 times under running water. Add 4 cups of water and soak for at least 10 hours.
Next morning, drain the water. Rinse the chickpeas again, transfer them to a pressure cooker, add baking soda, salt, and tea bags. Pressure cook for about 12 whistles over medium heat, until tender. Once the cooker depressurizes, open and check if the chickpeas are tender if not pressure cook for another 3 whistles. Discard the tea bags, do not squeeze the tea bags, as it will release bitter tannins. If you do not have a pressure cooker, cook the chickpeas in a regular pot with sufficient water until it is fork tender. Or you can use the canned ones, drain the water, rinse and use.
Whilst the chickpeas are getting cooked, you can start preparing the curry. Heat oil in a heavy bottomed kadai, once the oil is hot add in the cumin seeds and whole spices, sauté until they become fragrant.
Add in onion paste or finely chopped onion, sauté until they turn golden brown. Add a little salt to help them sweat faster.
Add in the ginger garlic paste next, sauté until fragrant.
Add in the tomato puree, sauté until oil begins to ooze from the sides of the pan.
Add in the chole masala, red chilli powder, cumin powder, anardana powder, turmeric powder, and amchur powder. Sauté the spices for another 30 seconds or until aromatic.
Add in the chickpeas next along with ginger juliennes, and slit green chillies. Mix well with the masala for another minute on medium heat.
Add in the reserved chickpea stock water. Mix well. Bring the curry to a boil. Check for seasonings and adjust salt accordingly. Cover, reduce the heat and let it simmer for 15 minutes for the flavors to mingle & deepen. Stir occasionally in between, for a thicker consistency, mash some chickpeas with the back of the ladle.
Sprinkle kasuri methi, mix and simmer for another 2-3 minutes. Check for seasonings an adjust accordingly. Switch off the heat. The curry will thicken as it sits. Serve hot with bhature, naan, kulcha, or any other flatbread, jeera rice/pilaf along with some pickled onions and lemon wedges!