Bring a large pot of water to a boil. Add 1 tbsp oil and a little salt. Add the noodles and cook according to package instructions until just cooked.
Drain the noodles and rinse under cold water to stop the cooking process. Drizzle 1 tbsp oil over the noodles and toss gently to prevent sticking. Set aside.
Heat a wok or large pan over high heat. Add the remaining 4 tbsp oil. Add the garlic and ginger. Sauté for a few seconds until fragrant.
Add the white part of the spring onions and stir-fry briefly.
Add the carrots and beans. Stir-fry for 1 to 2 minutes. Add the sugar and mix well. This helps the vegetables retain their vibrant color.
Add the cabbage and toss on high heat for a minute, keeping the vegetables slightly crisp.
Add the capsicum and stir-fry for another minute.
Add the soy sauce, ketchup, red chili sauce, vinegar, black pepper powder, red chili flakes, and salt. Mix well until everything is combined.
Add the cooked noodles and toss gently until the noodles are evenly coated with the sauces and vegetables. Finally add the green part of the spring onions,
Serve hot.