First, soak the dried rice stick in the hot water for 15 minutes. Then drain the water out and rinse with cold water. ( Or you can prepare by the packet instructions. )
Cut the beef into thin slices against the grain. Marinate with light soy sauce, corn starch, and cooking oil. Set it aside for 10-15 minutes.
Chop up the vegetables and set them aside. Combine the stir fry sauce ingredients in small bowl. Whisk it well until sugar dissolves.
Heat the large wok or pan over medium-high heat. Drizzle 1 tbsp of oil and fry the eggs and scramble them into small pieces. Remove from wok and set it aside.
In the same wok, drizzle 3 tbsp of oil. Add the marinated beef slices and sear one side for 2-3 minutes then filp the beef and stir fry for another 1-2 minutes.
Add chopped garlic and stir it well for a few seconds until fragrant. Add choy sum stem parts and toss it well for a few seconds and follow with the leaves.
Next, add the rice noodles and pour the sauce mixture in. Bring to heat to high. Combine everything well and continue stir fry until the sauce is absorbed and noodles become glossy.
Place the scrambled eggs in and make a quick toss. Transfer to serving plate and serve immediately.