Divide the noodles, pak choi and beansprouts between two serving bowls and lay the sliced beef on top. Bring the broth back to a simmer then divide between the two bowls. Scatter the spring onion ...

Drain; reserve 1 cup pasta water. Add butter to noodles and toss to combine. Meanwhile, in another large pot over medium-high heat, heat oil. Cook beef, breaking up with a wooden spoon ...