1 cup black lentils (probably split)
some tomato puree- maybe 1/2 cup
about 1/4 cup cream
1/2 tsp cumin
1/2 tsp coriander
1 green chili
2 tbsp butter
2 tbsp chopped onion
1/2 tsp chopped ginger
1/2 tsp chopped garlic
Put everything but the butter and cream in a pressure cooker and cook it for 1/2 hour. Open the lid by running it under cold water until the steam is done, then add the cream, cook 10 minutes. Add butter as a garnish (however that works).
If you don't have a pressure cooker, just cook it all in a pot. Soak the lentils for a couple hours beforehand.
Note about oil: sunflower oil and mustard oil are popular in India. Mustard oil is good for winters, it makes things last longer.
Source: cooking class in Delhi