Slice the lean sirloin steak into thin strips against the grain. In a mixing bowl, combine the steak with miso paste, half of the grated ginger, two minced garlic cloves, and a light sprinkle of black pepper. Toss until well-coated and allow the mixture to marinate for about 10 minutes.

Bring a medium pot of salted water to a boil over high heat. Once boiling, add the broccoli florets and blanch them for 2 minutes until they turn bright green and tender-crisp. Immediately drain the broccoli and rinse it under cold water.

In the same pot of boiling water, add the wholewheat noodles and the star anise along with sliced spring onions. Cook the noodles for about 5 minutes, stirring occasionally, until they are al dente and soft. Once cooked, drain the noodles, reserving a small cup of the cooking water.

Heat 2 teaspoons of rapeseed oil in a non-stick wok over high heat until shimmering. Add the marinated steak strips and stir-fry for about 1 minute until they change color and are just cooked through. Remove the steak from the wok.

In the same wok, add the remaining minced garlic, the rest of the grated ginger, and button mushrooms. Stir-fry for 3-4 minutes until the mushrooms are soft and golden, adding a splash of reserved noodle water if needed.

Return the cooked steak and blanched broccoli to the wok, tossing everything together to combine and heat through for about 1-2 minutes.

Drain the noodles and arrange them onto plates, then top generously with the stir-fried mixture. Drizzle with reduced-salt soy sauce and a splash of sesame oil.