Coat the chicken. In a large mixing bowl, toss the chicken pieces with cornstarch, salt, and pepper.
Pan-fry the chicken. Heat a wok or a large skillet over medium heat. Add 1 tablespoon vegetable oil to the wok, then add the chicken pieces. Cook the chicken for about 6 to 8 minutes, or until browned and cooked through. If your skillet isn’t big enough to fit all the chicken pieces in one single layer, cook the chicken in batches. Remove chicken from skillet; cover and set aside.
Sauté the aromatics. Add the remaining vegetable oil to the skillet and set it back on the burner over medium heat. To the hot oil, add the sliced scallions and cook for 30 seconds. Stir in the garlic and cook for 20 seconds, stirring frequently.
Meanwhile, make the sauce. In a mixing bowl, combine the chicken broth, soy sauce, bourbon, brown sugar, apple juice, apple cider vinegar, and ground ginger; whisk until thoroughly incorporated. Pour the sauce into the hot wok or skillet with the aromatics, cook for 3 minutes, and bring to a steady simmer.
Combine. Add the chicken back to the skillet and bring to a boil. Reduce the heat to medium-low and cook for about 5 to 8 minutes, or until the sauce is thickened. Remove from heat.
Finish and serve. Garnish with sesame seeds and sliced green onions, and serve over rice, noodles, etc.
