4 cups regular brown lentils
2 onions, diced
4 cloves garlic, minced
1 tablespoon minced ginger
4 tablespoons butter (optional)
5 tablespoons red curry paste
1 tablespoon garam masala
1½ teaspoon turmeric
2 teaspoon sugar
a few good shakes of cayenne pepper
2 cans tomato puree (29 ounces each)
1 teaspoon salt plus more to taste
½ cup coconut milk or cream
cilantro for garnishing
rice for serving