Start off by making the sauce: Mince 1 garlic clove and 1 tbsp ginger and cook it in a saucepan filled with 2 tbsp vegetable oil. Cook it over medium-high heat for 1 minute.
Add the ¼ cup brown sugar, 1 cup low sodium soy sauce, and ½ cup water. Bring to a simmer and cook over medium-low heat for 5 minutes.
Thinly slice the 2 lb. beef into small pieces. Pro tip: place the beef in the freezer 15-20 minutes prior to slicing to make thinner cuts without the meat sliding around.
Place the sliced beef in a large bowl and mix it with ⅓ cup cornstarch.
Heat ⅓ cup vegetable oil in a 14-inch wok and cook the beef in 2 batches to avoid overcrowding and mushy texture. Once cooked, remove the beef and set it aside.
In the same wok, cook 1 clove minced garlic over medium heat for 1 minute. Then add 1 cup sliced yellow onion and cook until translucent.
Add the beef back into the wok and pour in the sauce. Bring to a simmer for another 5 minutes.
Add 2 bunches of sliced green onion to the beef and stir for about 2-3 minutes. Serve warm over hot rice.
