400 gm piece flank steak, at room temperature
2 tbsp shiro (white) miso
2 tbsp grapeseed or vegetable oil
1 tsp sesame oil, plus extra to serve
200 gm mixed Asian mushrooms, such as shiitake and enoki
1 tbsp finely grated ginger
1 garlic clove, finely chopped
2 spring onions, thinly sliced, white and green parts reserved separately
200 gm soba noodles
1 tbsp soy sauce, or to taste
To serve: roasted sesame seeds
Brush steak with 1 tbsp miso, then drizzle with half the grapeseed oil.
Heat a frying pan over medium-high heat, add steak and cook, turning occasionally, until browned and medium-rare (8-10 minutes).
Transfer to a plate, cover loosely with foil and set aside for 15 minutes to rest, then thinly slice across the grain.
Add sesame oil and remaining grapeseed oil to pan, add mushrooms, ginger, garlic and white parts of spring onion and sauté until tender (2-3 minutes), then transfer to a plate.
Cook noodles according to packet instructions until al dente, drain and divide among warm bowls and top with mushrooms and steak.
Meanwhile, stir remaining miso, soy sauce and 500ml water in frying pan to combine, bring to a simmer, then pour onto noodles and serve scattered with spring onion greens and sesame seeds.