Rinse 1.5 cups of rajma under running water 2-3 times until the water runs clear.
Soak the beans in plenty of fresh water (at least double the amount) for 8 hours or overnight.
After soaking, drain the water and transfer the rajma to a pressure cooker.
Add 3 cups of water, 2 bay leaves, 1 black cardamom, 1 stick of cinnamon, and 0.5 teaspoon salt.
Cook on medium flame for 6-7 whistles, until the rajma becomes soft and mashable. Let the pressure release naturally.
Once the pressure releases, open the cooker, check if the rajma is cooked (it should mash easily). Remove the whole spices (bay leaves, cinnamon stick, black cardamom), and set the cooked rajma aside.
Heat 0.2 cup mustard oil (or any cooking oil) in a heavy-bottomed pan.
Add 1 teaspoon cumin seeds and let them splutter. Add 4-5 finely chopped onions and sauté until golden brown.
Step 5: Add Ginger-Garlic Paste
Add 1 tablespoon of ginger-garlic paste and sauté for 1 minute until the raw smell disappears.
Add 1 teaspoon turmeric powder, 1 teaspoon cumin powder, 2 teaspoons coriander powder, and 2 teaspoons Kashmiri red chili powder. Stir well, add a splash of water to prevent burning, and cook for 2 minutes.
Add 2 medium-sized pureed tomatoes (or ½ cup store-bought tomato puree) and cook for 5 minutes until the mixture thickens and the oil starts separating from the sides.
Add the boiled rajma and its cooking water to the pan. Adjust the consistency with extra water if needed.
Add 1 teaspoon garam masala and let the curry simmer on low flame for 10-12 minutes.
Add 1-2 finely chopped green chilies, 2 tablespoons chopped coriander leaves, and 1 teaspoon ghee for richness. Let it rest for 2 minutes before serving.
Serve Rajma Masala with rice, naan or roti.