In a small saucepan, simmer together the mirin, rice vinegar, miso, brown sugar and soy sauce for 5 minutes. Remove the heat then strain into a measuring jug and allow to cool for 15 minutes.
Pour the miso glaze over the salmon then marinade for at least 30 minutes but ideally overnight in the fridge.
In a large pan, saute the spring onion and garlic in a splash of sesame oil until fragrant.
Pour in the soy sauce, vinegar and brown sugar and add 4 tablespoons of water.
Allow the sauce to simmer until the sugar has dissolved. Add the cooked noodles then toss until coated in the sauce and sprinkle with sesame seeds.
Preheat the oven to 220°C/430°F.
Transfer the salmon to a parchment or foil lined baking dish.
Bake for 7-10 minutes until the salmon is caramelized and just cooked.
Remove from the oven then serve over the noodles with coriander/cilantro, sesame seeds, spring onion and chillies.