Freeze the sirloin steak for 15-30 minutes to make slicing easier. Slice the partially frozen beef into thin strips and trim away any excess fat.
2
Sprinkle the sliced beef with baking soda, black pepper, and soy sauce. Mix thoroughly with tongs to distribute the baking soda evenly. Let it sit for a few minutes.
3
Whisk together the beef stock, soy sauce, oyster sauce, brown sugar, and cornstarch in a bowl. Mix well and set aside.
4
Mince the garlic and prepare the broccoli florets. Heat a large skillet over medium-high heat with neutral oil until it's very hot.
5
Add the marinated beef to the hot pan in a single layer. Cook for about 1 minute per side until mostly cooked through. Remove the beef and set aside.
6
Add the minced garlic to the pan and cook for about 30 seconds until fragrant. Add the broccoli florets and stir-fry for 2-3 minutes.
7
Return the cooked beef to the pan. Pour in the prepared sauce and cook for about 2 minutes, stirring occasionally, until the sauce thickens and becomes glossy.