Mix soy sauce, hoisin sauce and kecap manis in a bowl to make the stir-fry sauce.

Slice spring onion and bok choy for the stir-fry.

Cook udon noodles as per packet instructions. Drain and set aside. (see notes)

Heat oil in a large wok on high heat and stir-fry onion for 1-2 minutes until translucent.

Fry ginger and garlic for a few seconds until fragrant.

Add beef mince and break it up with a wooden or metal spatula. Spread beef mince in the wok and allow it to cook for a 5-6 minutes without tossing, so the beef crisps, chars and caramelizes. When all liquid has evaporated, toss the cooked beef around.

Add the greens and cook for 30 seconds until just wilted.

Add cooked noodles and stir-fry sauce to the wok.

Toss and stir-fry on high for a couple of minutes until heated through. Serve