1. Soak the lentils (brown and red separately) for 30 minutes in lukewarm water. Drain.
2. Heat the butter in a saucepan, add the onions and whole spices, then stir-fry until the onions are soft.
3. Mix the tomato paste or chopped tomato with the ground spices. Add to the saucepan, with the sweet potatoes and/or brinjals. Add the garlic and ginger, and stir-fry until fragrant.