Mix all the ingredients of the marinade together and marinate the fish for at least one hour.
Bring a pan of water - with one small piece of khombu in it - to the boil. Add the noodles and stir to ensure that they don't stick together. Boil for 5 minutes.
While boiling, heat the wok with 1 teaspoon of sesame oil and 1 tablespoon of olive oil. Add the shallots, mushrooms and fish (reserving the marinade). Stir-fry for 2-3 minutes. Add the remaining vegetables and stir-fry for another 3 minutes, adding the marinade at the end. Stir through for a further 1 minute.
Drain the noodles and serve under the Asian fish.