Roast the red lentils in a pot at medium heat while stirring constantly until some lentils are slightly browned. Put the lentils in a sieve and wash them under running water. Return to the pot. Add 900 ml water, bay leaves, butter and 1 1/2 tsp salt. Heat everything up, bring to the boil, cover and simmer over medium heat for about 30 minutes
Peel and chop the onion. Wash, clean and chop the tomatoes. Peel and grate ginger. Crumble chillies with your fingers. Heat oil in a pan. Add mustard seeds and fry briefly. Add cumin, chilli, ginger, coriander and turmeric. Stir-fry for about 30 seconds. Add tomatoes and onion and fry for 1-2 minutes
After about 20 minutes of cooking time, add the tomato mixture to the lentils and finish cooking. Season the dal with lemon juice and salt if necessary. Indian flat bread and mango lassi taste good with it