Coconut curry red lentil soup

Name: Coconut curry red lentil soup
Ingredients: 1 cup depuy/brown lentils; 1 cup red split lentils; 2 tablespoons butter/ghee/coconut oil/olive oil; 1 small onion, diced; 2 + 1 tablespoons curry powder; 6.5 cups water; 2 tablespoons freshly grated ginger; 1/4 c + 2t ketchup (or an 80 ml can of tomato paste, with lemon juice and sugar added to taste); 14 ounces can of coconut milk (low-fat or regular); 2 teaspoons salt; for garnish: sliced green onions, or toasted large-flake coconut, or chopped cilantro