Mix the teriyaki ingredients (soy sauce, mirin and sugar) in a small pan. Bring to the boil to dissolve the sugar, then bubble for about 3 mins till thickened.
Cook the noodles and drain. Preheat the broiler and put a steamer on. Lay the salmon, skin-side down, on an oiled baking sheet, brush with olive oil, season with pepper and grill for 3 minutes Meanwhile, steam the pak choi for 3-4 minutes.
Heat both the oils for the noodles in a wok, tip in the garlic and stir-fry for 1 minute
Add the noodles and stir-fry for 1 minute Keep the noodles and pak choi warm.
Turn the salmon over, brush with teriyaki sauce, and grill for 1 minute Brush again to glaze. Serve with noodles and pak choi, top with scallions, ginger and sesame seeds, and drizzle with remaining sauce.
GIVE IT A FANCY FINISH:.
Cut shreds of scallion and fresh root ginger, and leave in water in the fridge to crisp and curl. Scatter over the salmon.