1. Sweat onion in hot oil, then add the garlic, ginger, and spices and continue cooking the mixture for about a minute. 2. Stir in the broth and red lentils. Simmer for about 20 minutes.
3. Bring the soup up to a simmer and let it cook for about 20 minutes, or until the lentils are very soft. 4. Stir in the coconut milk and tomatoes. Let the soup continue simmering for about 5 minutes more. By now the lentils should be mostly broken down, giving your soup a thick, almost creamy texture.
5. Take the pot off of the burner and stir in some fresh lemon juice, along with salt and pepper to taste.