Wash the mung beans under cold running water until the water runs clear. Soak them for at least 8 hours, preferably overnight, in plenty of water.
Boil the mung beans in 750 ml water with 1 teaspoon salt for 20 minutes. Drain and let it dry with steam for a while. (keep the strained liquid in a bowl)
Heat the sunflower oil in a frying pan over medium heat and add the cumin seeds, let it splutter for 15 seconds. Then fry the onion for 3-4 minutes. Add the ginger-garlic paste and fry for 3 minutes. Stir in the tomatoes and fry them gently for 5 minutes, stirring.
Add the rawit peppers, turmeric powder, chili powder, cumin powder, coriander powder and fry for a further 2 minutes.
Add the cooked mung beans and 350 strained liquid and bring to a boil. Continue cooking for 5-7 minutes. Add garam masala and coriander leaves and stir well. Serve this dahl with chapati (Indian flatbread) and/or rice.