In a large bowl, add cut chicken, water, oyster sauce, cornstarch, a splash of soy sauce, and vegetable oil. Using gloves, mix ingredients well. Set aside to marinate - remember the longer you marinate - the better the flavor.
In a small bowl, combine cornstarch and water to make a thickening slurry.
Bring water to a boil, then add salt. Add broccoli, and let soften for about 2-3 minutes and then quickly remove and set aside.
In a container or bowl add chicken stock and microwave for a minute or so. Then add the sugar, soy sauces, oyster sauce, white pepper, and sesame oil. Whisk with a fork till everything is combined.
In a hot wok or large pan, add oil and sear the chicken (drain the liquid as much as possible) If the chicken was cut thin enough and wok is hot enough, this should take about 4 minutes to sear and turn white color. (it will cook more in marinade later.) Remove chicken and set aside.
Add more oil to the wok and add in carrots. Saute carrots a bit then add in the chopped garlic. (can season with a little pepper if you like - soy sauce is salty so I don't recommend adding more salt)
Add rice wine vinegar to help you stir fry the carrots. Remove and set aside.
Add marinade to pan and mix in the corn starch slurry. Whisk till thick.
Toss in chicken, carrots, and broccoli and stir fry together mixing every so often so that all the ingredients are incorporated.
Serve with rice and enjoy! (Top with some toasted sesame seeds if you want to add a little texture)