Heat ghee in a pan over medium heat. Add cumin seeds, hing, and green chili. Sauté briefly until fragrant.
Add chopped onions and cook until they turn golden brown. Stir in the ginger & garlic paste and cook until the raw aroma disappears.
Pour in the tomato puree and mix well. Add red chili powder, coriander powder, black pepper, and turmeric. Cook until the oil separates from the masala.
Add cooked rajma along with rajma water. Stir well and let it simmer for a few minutes to absorb the flavors. Season with salt to taste.
Sprinkle garam masala and mix well. Turn off the heat.
Garnish with freshly chopped coriander leaves and serve hot with rice or roti.