Sweet Potato with Toasted Coconut

Name: Sweet Potato with Toasted Coconut
Ingredients: 3 medium sweet potatoes (1 3/4 pound total), peeled and cut into 1-inch pieces (about 5 cups); 2 cups water, divided; 1/4 teaspoon ground turmeric; 1/8 teaspoon cayenne pepper; Salt; 1/2 cup grated dried unsweetened coconut; 1/2 cup canned kidney beans, rinsed and drained; 1/2 teaspoon minced garlic; 1/2 teaspoon ground cumin; 1 small fresh green chile, such as serrano, Thai, or jalapeño, slit lengthwise with stem end intact; 2 tablespoons vegetable oil; 1/2 teaspoon brown mustard seeds; 1/8 teaspoon hot red pepper flakes; 10 fresh curry leaves (optional)