Soak 140g of whole black urad dal and 40g of dried kidney beans in plenty of water for 8-9 hours; drain and rinse.
Cover with 4 cups of fresh water. Boil vigorously for 30 minutes, then simmer, partly covered, until completely soft, adding water to keep submerged.
Melt 3 tablespoons of butter. Fry 50g of chopped onion until golden. Add 2 teaspoons of ginger-garlic paste and 1 teaspoon of chopped green chili; stir for 1 minute.
Add 200g of puréed tomatoes, ½ teaspoon of red chili powder, and 2 pinches of ground nutmeg. Cook until thick and the butter separates.
Add the cooked dal and beans with their liquid, and 1 cup of water. Simmer uncovered for 25 minutes, stirring often; add water if needed. Season with salt.
Stir in ¼ cup of light cream, ½ teaspoon of garam masala, and ¼ teaspoon of crushed dried fenugreek leaves. Remove from the heat.
