Cook the soba noodles according to the packet instructions. Drain and rinse with cold water (to stop them overcooking).
Finely slice the portobello mushrooms and add to a frying pan with a splash of olive oil. Add a tablespoon of soy sauce, and cook the mushrooms until they begin to char. Remove from the heat.
Grate the carrots and red cabbage, and finely slice a red pepper. Mix with the noodles.
Sauce time. Whisk together 2 tbsp of soy sauce, the juice of a lime and a tbsp of sriracha. Add 3 tbsp of sesame oil while whisking.
Combine the dressing and the noodles, top with mushrooms and sprinkle over the nori seaweed (broken into little pieces) and a handful of chopped coriander.