Mix the chicken, 3 tablespoons water, 2 teaspoons oyster sauce, and ⅛ teaspoon white pepper. Set aside for 5 to 10 minutes until all the liquid has been absorbed by the chicken. Adding the extra water will really keep your chicken moist and tender. Lastly, mix in 1 teaspoon canola oil and 1 tablespoon cornstarch, and set aside.
In a separate bowl, mix together all the sauce ingredients and set aside.
Heat your wok over high heat. Spread 2 tablespoons canola oil along the perimeter of the wok until just smoking.
Add the marinated chicken breast, spreading the pieces evenly in the wok. Fry for 1 minute on each side, and transfer back to the bowl. The chicken should be browned on the outside and will be about 80% cooked.
Add another tablespoon of oil to the wok, along with the ginger, and fry for 5 seconds before adding the minced garlic. Immediately add the red bell pepper and chopped water chestnuts. Stir fry for 30 seconds.
Next, add the scallions, and spread your Shaoxing wine around the perimeter of the wok. Give everything a quick stir fry for 10 seconds.
Pour in the sauce mixture you made earlier, using your wok spatula to deglaze the sides of the wok. Add the chicken and any juices that may have collected in the bowl. Once everything comes to a simmer, add your roasted cashews.
Stir up your cornstarch slurry, and add to the stir-fry. Add more cornstarch slurry if you like a thicker sauce, less if you prefer thinner. Bring to a simmer to thicken the sauce, and continue stirring to combine evenly. Plate and serve immediately with a bowl of rice!