Begin by rinsing the dried chickpeas under cold water. In a large pot, cover the chickpeas with several inches of water and add 1 teaspoon of baking soda. Soak them overnight, or for a minimum of 8 hours. The next day, drain the chickpeas and rinse them again. In the same pot, add fresh water, bring it to a boil, and cook the chickpeas for about 1 hour, or until they are tender. Drain and set aside.
In a large skillet, heat the 2 tablespoons of vegetable oil over medium heat. Once hot, add the sliced onion and sauté for about 5-7 minutes, or until the onions are golden brown. Next, add the cumin seeds and stir for about 30 seconds to release their flavor.
Stir in the minced garlic, grated ginger, and minced green chili. Cook for another 2-3 minutes, allowing the mixture to become fragrant.
Add the undrained can of whole plum tomatoes and tomato paste to the skillet. Use your wooden spoon to break the tomatoes apart. Sprinkle in the garam masala, ground cumin, red chili powder, ground turmeric, and salt to taste. Stir well to combine.
Add the cooked chickpeas to the skillet, mixing them into the sauce. Let everything simmer together for 15-20 minutes on low heat, allowing the flavors to meld beautifully. If the mixture is too thick, feel free to add a splash of water.
Once done, taste and adjust the seasoning if necessary. Serve your homemade chana masala hot, garnished with fresh cilantro leaves, sliced green chilies, quartered grape tomatoes, and thinly sliced red onion. Pair it with warm naan bread for a complete meal.