Step 1. Simmer lentils, partially covered, for about 25 minutes, or until the lentils lose their shape and are very tender. Skim off the scum with a slotted spoon.
Step 3. Add onion and cook for about 7 minutes. Add the garlic, ginger, coriander, cumin, turmeric, cayenne pepper, and the green chili peppers. Cook for 30 seconds.
Step 4. Stir in the tomatoes and cook for 2 minutes more. Add cooked lentils and water, plus vegan butter (if using). Simmer until the desired consistency.