How to Make It
In a large enameled cast-iron casserole or Dutch oven, heat the oil. Add the onion, garlic, ginger and lemongrass and cook over high heat, stirring, until golden, about 5 minutes. Add the curry powder and cook, stirring, until fragrant. Add the coconut milk, fish stock, fish sauce, brown sugar and chili-garlic sauce. Season with salt and pepper and bring to a boil.
Add the potatoes and simmer over low heat until tender, about 30 minutes. Add the fish and simmer, stirring occasionally, until just cooked through, 5 to 10 minutes longer. Stir in the cilantro. Serve the curry with rice and lime wedges.