Drain the soaked chickpeas and rinse them. Add to a pressure cooker with 3.5 cups of fresh water, the tea bag (or amla), bay leaf, cardamom, cinnamon and salt. Pressure cook for 5 to 6 whistles (about 18 to 20 minutes) until the chickpeas are completely soft and mash easily between the fingers.
Discard the tea bag and whole spices, but keep all the cooking water — it becomes the gravy and carries the dark colour.
Heat the oil or ghee in a heavy pan and let the cumin seeds crackle. Add the onion paste and cook on medium heat for 10 to 12 minutes, stirring often, until it turns a deep golden brown and the oil separates.
Add the ginger-garlic paste and cook for a minute until the raw smell goes.
Pour in the tomato puree and the slit green chillies. Cook for 8 to 10 minutes until the masala thickens, darkens and leaves oil at the sides.
Lower the heat and add the chole masala, chilli powder, coriander powder and turmeric. Stir for a minute — dry spices burn fast at this stage.
Add the boiled chickpeas along with their water. Mash a handful of chickpeas against the side of the pan with the spoon; this is what thickens the gravy naturally.
Simmer uncovered for 12 to 15 minutes until the gravy coats the chickpeas. Adjust salt, and add amchur now if you want more tang.
Rest for 10 minutes off the heat — chole always tastes better after a short rest. Garnish with ginger juliennes and coriander, and serve hot with bhature, lemon wedges and sliced onion.