1. Cook the noodles – Follow the packet instructions for the egg noodles, but cook them just one minute less than suggested so they remain slightly firm (pliable rather than soggy). Rinse under cold water and set aside.
2. Cook the beef – Heat a large heavy-based frying pan over medium-high heat. Add the olive oil, then garlic and ginger. Cook for about 30 seconds until fragrant. Add the minced beef and cook for about 2-3 minutes, breaking it up, until browned.
3. Make the sauce – To the browned beef, add the sweet chilli sauce, brown sugar (if using), tamari (or soy sauce), dark soy sauce and rice wine vinegar. Cook this mixture for about 2-3 minutes, stirring, until the sauce thickens slightly and starts to caramelise on the beef.
4. Add the vegetables – Add your frozen vegetables. Cover with a lid and cook for about 2-3 minutes (or until the vegetables reach your preferred tenderness).
5. Thicken the sauce – In a small bowl, combine the water and the cornflour until smooth, then add this mixture to the stir-fry. Cook for 1-2 minutes, stirring, until the sauce becomes glossy and thick.
6. Add the noodles – Add the cooked noodles and the sliced spring onions (reserve 1 tbsp for garnish). Stir everything together for about 1 minute, until the noodles are heated through and evenly coated in the sticky sauce.
7. Serve – Plate up the noodles, top with the remaining spring onion slices and drizzle with chilli oil if you like a bit of extra heat.

Note: You can omit the brown sugar completely if your sweet chilli sauce is already quite sweet.