Bring a medium pan of water to the boil. Add the noodles and cook for 3 minutes until tender. Drain and set aside.
Heat the oil in a large wok. Add the onion and stir-fry for 2-3 minutes, until beginning to soften. Add the chilli, garlic and five spice paste and stir-fry for a further 1 minute.
Add the peppers, carrot and broccoli to the wok and stir-fry for 3 minutes, until just tender.
Add the leftover roast beef to the wok along with the cooked and drained egg noodles, soy sauce and 100ml water. Heat through, stirring, then divide between 4 bowls and serve immediately.