If using dried kidney beans, after soaking overnight, boil until soft (about 30 mins). If using canned kidney beans, do not drain or rinse, the canning liquid will help emulsify the dish.
Heat oil in a pot and add cumin seeds.
When the cumin seeds have turned a shade darker, after about 1 minute, add the onions.
Once the onions have started to sweat, add the ginger and garlic. Sauté until it reaches a dark brown shade, and everything has broken down fully, about 10 mins. Deglaze with water as needed.
Add jalapeño, turmeric, and salt and sauté for one minute.
Add the tomatoes and cook for about 15 mins, until fully broken down. If using tomato sauce, use the back of your spoon to assist the process.
Add the kidney beans and mix gently.
If using canned kidney beans, add 2 cups of water. If using soaked and boiled kidney beans, add 1 cup of water.
Simmer for 20 minutes.
While the rajma simmers, add the rinsed rice, water, cumin seeds, salt, and oil to another pot and simmer until all the water has absorbed.
Garnish the rajma with cilantro and serve over the rice.