There are rumours Mongolian lamb (or beef) was named in honour of an ancient style of Mongol cooking, whereby meat is stir-fried in a warrior's shield. We can't confirm nor deny this story, but what we can do is insist you try this fast and full-flavoured weeknight stir-fry. It's fine to just use a wok or frypan, if you don't have a warrior shield on hand.
Peel and chop onion into 3cm pieces. Peel and thinly slice garlic.
Trim and chop snow peas into thirds. Chop cabbage into 2cm pieces. Chop bok choy into bite-sized pieces.
Heat sesame oil in a large frypan or wok over medium-high heat. Add onion and a pinch of salt and cook, stirring occasionally, for 2–3 minutes or until onion has softened and caramelised.
Add lamb mince and cook, breaking up with a wooden spoon, for 5–6 minutes or until caramelised. Add garlic to frypan and cook, stirring continuously, for 30 seconds or until fragrant.
Add snow peas, bok choy and cabbage and cook, stirring occasionally, for 2–3 minutes or until slightly tender.
Add noodles, mirin, oyster sauce, soy sauce and 40ml (2 tablespoons) water. Stir with tongs to loosen noodles and coat in sauce. Divide stir-fry between bowls to serve.