Wash and dry the whole green chilies. Heat a small frying pan on low medium heat, add the oil and green chilies, and cover the pan. Shake the pan slowly to move the chilies around. Notes: it is important to keep the pan cover chilies will splatter. Cook the chilies for about 2 minutes turn off the heat, wait till it stop splattering and remove the lid chilies should be light brown if it is not cook for another minute. Remove and keep aside.
Place chickpeas in a bowl and lightly mash. Add the potatoes and all the ingredients ginger, green chili, red pepper, salt, black salt, black pepper, mango powder, sugar, roasted cumin powder, lemon juice, and cilantro mix it well.
Let it sit for at least fifteen minutes or more, chickpeas and potatoes will absorbed the flavor of spices.
Serve the aloo chana chat with side of tomatoes, fried green peppers and lemon wedges.