In a separate saucepan, heat olive oil and butter.
Once the butter has melted, add the chopped onions and chili peppers and sauté for 5 minutes or until soft. Add the minced garlic and diced tomatoes and sauté an additional minute.
Season with cumin, chili powder, turmeric, and salt.
Once the lentils are finished cooking, stir the tadka into the pot. Taste and add more seasoning if needed. Allow the dal to simmer for a few minutes so the flavors can come together.
Serve with basmati rice and toasted naan bread.