Put the onion, carrot and sunflower oil into a wok and cook over a medium heat for about 6–7 minutes, stirring frequently, until the onion is just starting to turn golden.
Add the mushrooms, cabbage and broccoli to the wok along with the white parts of the spring onions, the garlic and grated ginger. Stir-fry over a medium heat for about 2 minutes, until the vegetables are tender.
Add the noodles, mirin, soy sauce and rice vinegar and stir-fry until the noodles are hot through.
Drizzle with sesame oil and scatter with the green parts of the spring onions and the sesame seeds, if using, and top with a little pickled ginger, if liked.
