Soak rajma in water overnight or minimum 6 hours. Add Rajma with 2 cups of water and turmeric powder in a pressure cooker and cook till kidney beans are soft and easily mash between fingers.
Heat a sauce pan and add oil to it. When the oil is warm add cumin seeds, carom seeds and let it crackle.
Add onion and saute till translucent. Now add ginger and garlic and saute.
Add chopped tomatoes to it. Saute for few minutes till the tomatoes are nicely cooked and mushy.
Add garam masala, red chili powder, turmeric powder and mix well.
Now add cooked Rajma and salt and mix well. If you feel the gravy is too dry, add little more water. Close the pan and let it cook for few minutes.