1. In a mixing bowl, combine the fish fillets, egg, breadcrumbs, fish sauce, salt, and pepper. Mix well and form into small patties.
2. Heat oil in a pan over medium heat. Fry the fish cakes until golden brown on both sides. Remove and set aside.
3. In the same pan, add a bit more oil if needed. Sauté the onions and garlic until fragrant.
4. Add the curry powder and cook for another minute.
5. Pour in the coconut milk, soy sauce, lime juice, and sugar. Stir well and bring to a simmer.
6. Add the fish cakes back into the pan and simmer for another 10 minutes.
7. Serve hot with rice or naan.