Cut beef into thin pieces(cut against the grain, as shown on video)
Marinate beef: in a bowl, mix together beef and marinating ingredients, make sure each beef pieces are coated.
In a large wok (or skillet)over medium to high heat, when the wok is hot, oil the wok with cold cooking oil, stir fry marinated beef until done. Set aside.
Blanching broccoli and carrot: bring enough water to boil, carefully add in broccoli florets and carrots, cook until the water is boiling again. Raise with cold water and drain
Return the wok to the stove. Add 1 tbsp cooking oil, garlic, soy sauce, oyster sauce, sugar, and 1 tbsp water, cook until fragrant, then add broccoli, carrot, beef, cornstarch slurry, red chili slices and squeeze lemon juice. Toss and cook until mixed well.