In a small bowl, add in your oyster sauce, white sugar, light soy sauce, and 1/2 cup of water, and mix everything well together.
Mince 3-4 cloves of garlic and set it aside.
Heat up a wok on medium-low heat and once the wok is hot (i.e. steam coming out) add your cooking oil to the wok.
Once the oil is hot, add your minced garlic to the wok.
Stir-fry the garlic for roughly 1 minute until it turns golden yellow and crispy and then immediately add the sauce to the wok.
Mix everything well together and then turn up the heat to medium-high.
Prepare a cornstarch slurry by combining the cornstarch with the water and mixing it together until it turns into liquid form.
Once the sauce starts to bubble, stir the sauce in a circular motion and then slowly pour the cornstarch slurry into the wok while stirring the sauce.
Mix everything well together and once the sauce thickens, turn off the stove and transfer the sauce over to a bowl.
Once the Chinese broccoli has dried (make sure there’s no excess water on the leaves!), transfer them onto a plate.
Pour the sauce on top of the Chinese broccoli and serve!