Boil the noodles for 3 mins in a large pan, drain and rinse under cold water through a sieve and set aside to drain completely.
Heat the grill to high. Mix together the miso paste, balsamic vinegar, soy sauce and paprika to make the miso glaze and brush over the salmon fillets with a pastry brush. Lay the salmon skin side down on a greased baking tray and grill for 6-8 mins until just cooked through.
Heat the oil in a wok and stir-fry the garlic, ginger, spring onions and chillies for a couple of mins until soft, then add the cooked noodles, beansprouts and coriander. Toss everything together until well combined and turn off the heat. To finish, stir the fish sauce into the stir-fried vegetables and noodles, then pile onto plates, topping with the salmon.