Heat 1 tablespoon oil in a hot non-stick wok or frying pan over high heat. Cook lamb in batches for 2 to 3 minutes or until browned, remove from wok and set aside on a plate.
Add remaining oil over medium-high heat then add garlic, ginger and red onion to wok and stir-fry for 2 mins. Add corn, snow peas and broccolini and stir-fry for a further 2 to 3 minutes. Add pak choy and cook for a further minute. Stir in Mongolian paste and ¼ cup water and cook for another 1 minute. Return lamb to wok, toss well to heat through and season.
Serve lamb stir-fry on a bed of soba noodles topped with coriander and chilli, if desired.