1. Start by marinating the fish. Whisk together the fish sauce, ginger, sugar and turmeric in a mixing bowl with a good grinding of black pepper. Toss the fish in the marinade, making sure it's well coated; set aside for 30 minutes.
2. Meanwhile, soak the noodles in just-boiled water for 5 minutes, then drain and rinse under cold water. Toss with a tiny splash of oil and set aside to dry on kitchen paper. Make the dipping sauce by mixing all the ingredients together with 3 tbsp cold water; set aside.
3. Place a large frying pan over a high heat and add the oil. When smoking hot, add the fish. Leave for 1 minute so it gets a little colour, then turn carefully and fry for another minute. Turn again and fry for a fi nal minute, then set aside on a plate.
4. Lower the heat to medium, add the onion and garlic and fry for 10 minutes, stirring regularly, until softened and turning golden. Return the fish and add the dill, gently and briefly stir-frying until everything is warmed through. Divide the noodles between 2 plates, top with the fish mixture, scatter with the peanuts and serve with the dipping sauce and lime wedges.