To the melted butter add garlic, ginger, and onion. Cook for 2-3 minutes, until onions soften.
Add in the cayenne pepper, cumin, curry, and turmeric. Stir to combine well.
Add canned tomatoes and stir well.
Pour in the coconut milk and stir well.
Add lentils to the pan and stir well. Bring mixture to a boil. Put lid on pan, turn heat down to low and simmer for 25-30 minutes, stirring occasionally.TIP - If the mixture has thickened too much and the lentils aren’t quite tender enough yet (you don’t want them mushy), you can add the optional water and let it cook until lentils are done.
Notes
We prefer to use green or brown lentils because they soften nicely, but you can also use red lentils. Red lentils will be even creamier if that's the consistency you prefer, but do note that they cook faster than green or brown lentils.
We have not tried using canned lentils for this recipe, but I don't see why they wouldn't work. Because they are already cooked and you only need to warm them up, you can add them in toward the end of the recipe.