Cook the noodles in a large pan of boiling water, according to the packet instructions. Refresh in cold running water, then drain and toss into a bowl with the sesame oil.
Heat half the groundnut oil in a wok over a high heat until the oil starts to shimmer. Add the duck breast, season with salt and stir-fry for 2–3 minutes until browned. Tip the meat on to a plate and set aside while you return the wok to the heat.
Wipe the wok clean with kitchen paper, then add the remaining oil. Once it's hot, add the leek and stir-fry for 1 minute. Toss in the garlic, ginger, chilli, mangetout and bean sprouts and stir-fry for 1 minute. Return the meat to the pan, pour in the soy sauce, rice wine and honey and stir-fry for 1 minute. Finally, add the noodles and chopped coriander, stirring until the noodles are steaming hot. Garnish with a few whole coriander leaves and serve.