Thai Coconut Curry Lentil Soup

1 tablespoon olive oil

1 cup finely chopped onion
1 teaspoon minced ginger
1 teaspoon minced garlic 
1-2 teaspoons Thai red curry paste (if you like it spicy, use the full 2 teaspoons)
6 cups water
1 cup red lentils, picked through for stones, and rinsed well
1 medium sweet potato, cut into 1/2" pieces
1/4 teaspoon turmeric
1 teaspoon salt
1/4 cup coconut milk
fresh cilantro, for garnish

Heat olive oil in a medium saucepan. Add the onions, ginger and garlic. Cook over medium heat until softened, about 3-4 minutes. Stir in Thai red curry paste, and cook several minutes or until fragrant. Add water, lentils, sweet potatoes and turmeric. Bring to a boil, then reduce heat to medium-low, cover and cook about 20-25 minutes or until lentils and sweet potatoes are soft. Add salt and stir in coconut milk. Cook five more minutes. Garnish with fresh cilantro.