Heat oil in a pressure cooker and sauté cumin seeds, fennel seeds, green chillies, and onions till lightly browned and fragrant. Add in spices and ginger-garlic paste, and fry for a few seconds.
Add in the chopped tomatoes and salt, and cook for a few minutes to combine well. Add lentils, and enough water to cover them. Pressure cook for 15-20 minutes till lentils are soft and done. Stir in more water if you want a much thinner consistency, and let it come to a boil.
Garnish with fresh coriander leaves, and serve warm with a big bowl of rice.