Black Pepper Chicken

peanut oil (or other mild-flavored cooking oil)

boneless skinless chicken breasts, cut into bite-sized pieces

small bell pepper, cored and thinly-sliced

small red onion, peeled and thinly-sliced

stalks celery, thinly-sliced on a bias

garlic cloves, peeled and minced

low-sodium soy sauce

cornstarch

oyster sauce

rice wine vinegar

ground ginger

optional toppings: thinly-sliced green onions, toasted sesame seeds

freshly ground black pepper (to taste)