Method. In a large saucepan, heat the coconut oil. Add the onions and peppers and cook over moderate heat, stirring occasionally, until tender, 10 minutes. Add the curry paste and cook, stirring, about 2 minutes. Add the ginger and garlic and cook until fragrant, about 1 minute. Add the sweet potatoes and 2 quarts of water and bring to a simmer. Cook until the sweet potatoes are tender, about 25 minutes. Remove from the heat. Stir in the coconut milk and lime juice. In batches, puree the soup until smooth. Serve hot, garnished with coconut flakes and cilantro sprigs. The soup can be refrigerated for 3 days.