Finely crush the ginger, garlic and deseeded green chilli in a mortar and pestle
Grate the onions
Purée the tomatoes
Heat oil in a pot
Add cumin seeds and let them splutter
Add the grated onion with a pinch of salt and stir in the ginger-garlic-chilli paste. Cook slowly until light golden/brown
Add red chilli powder, turmeric, coriander powder, and garam masala. Cook until the oil starts to bubble and spices bloom
Pour in the tomato purée and some salt. Simmer until it deepens in colour and the oil starts separating
Stir in ¼ tsp sugar to balance the acidity of the tomatoes
Add the beans along with their liquid
Pour in 1 cup warm water
Let everything simmer gently so the beans soak up all the spicy, rich flavour
Crush Kasuri Methi between your palms and stir it in towards the end
Do a final salt check
Serve with a generous dollop of sour cream
