Boil 100 grams of Hakka noodles as per the instructions on the packet. Drain the water and let the noodles cool down.
Heat oil in a kadai or deep frying pan and deep fry the boiled noodles until they turn crispy and golden brown. Remove the noodles from the oil and place them on a paper towel to absorb excess oil.
In a large mixing bowl, combine 1/4 cup finely chopped onion, 1/4 cup finely chopped capsicum, 1/4 cup shredded cabbage, 1/4 cup grated carrot, and 2 tablespoons chopped spring onion greens.
In a separate bowl, mix 2 tablespoons tomato ketchup, 2 tablespoons red chili sauce, 1 tablespoon soy sauce, 1 tablespoon vinegar, and 1/2 teaspoon black pepper powder to make the sauce.
Pour the sauce over the vegetables and mix well.
Add the crispy fried noodles to the vegetable mixture and toss gently to coat the noodles evenly with the sauce and vegetables.
Garnish with some more chopped spring onion greens and serve immediately.