Also great with this sauce: grilled chicken breasts or vegetable skewers.
In a large heavy saucepan, heat the coconut oil over medium. Add the shallots and cook, stirring often, until softened, 5 to 7 minutes.
Add the ginger and turmeric and cook, stirring often, until aromatic, about 1 minute. Add the curry paste and stir until fragrant, 1 to 2 minutes. Add the sweet potatoes and stir until coated. Stir in the coconut milk and simmer until the potatoes are tender, 10 to 15 minutes. Add the fish sauce and brown sugar.
Add the shrimp to the sauce. Cover and cook until the shrimp are opaque in the centers, 2 to 3 minutes; season with salt and pepper.
Garnish with cilantro. Serve with the naan and lime wedges.