Soak the noodles in hot water for 1-2 minutes or until soft, then drain.
Peel and devein the prawns and cut each prawn along the back so it opens like a butterfly (leave prawn joined along the base and at the tail, leaving the tail attached).
Combine the tamarind with the fish sauce and palm sugar in a bowl.
Heat 1 1/2 tablespoons oil in a wok or fying pan and stir-fry the garlic over a medium heat until light brown. Add the prawns and cook for 2 minutes.
Using a spatula, move the prawns out from the middle of the wok. Add another 1 1/2 tablespoons oil to the wok. Add the eggs and stir to scrample for 1 minute. Add the noodles and chives and stir-fry for a few seconds. Add the fish sauce mixture, chilli powder, dried shrimp, preserved turnip and half of the peanuts. Add half of the bean sprouts and spring onions. Test the noodles for tenderness and adjust the seasononing if necessary.
Spoon onto the serving place and sprinkle the remaining peanuts over the top. Garnish with shredded chillies and a few coriander leaves. Place the lime wedges and remaining bean sprouts and spring onions at the side of the dish and serve.