Put the fish fillets in a large, non-reactive shallow dish. Mix together the turmeric, curry paste, lemon juice and sunflower oil and pour over the fish. Season, then toss to mix well and set aside.
Put the rice noodles in a heatproof bowl and pour over boiling water to cover. Leave to soak for 3–4 minutes, then drain and refresh under cold running water. Drain again and set aside.
Thread 2 metal skewers through each fish fillet to keep them flattened while cooking, then place under a preheated medium-high grill for 6–8 minutes or until just cooked through.
Meanwhile, heat the vegetable oil in a large wok or frying pan until hot, add the chilli, spring onions and drained noodles and stir-fry over a high heat for 2–3 minutes or until piping hot, then stir in the mint and coriander and season.
Divide the noodles on to warm serving plates or into shallow bowls. Top each with the grilled fish and scatter over the chopped chilli-roasted peanuts. Scatter with extra chopped mint and serve immediately.