Toss chicken with 3 Tbsp cornstarch, salt and lemon pepper until evenly coated.
In a large 12-inch skillet, heat 3 Tbsp oil over medium-high heat. Add chicken to pan in a single layer so each piece of chicken is in contact with the hot skillet.
Brown chicken for 1 - 1 1/2 minutes per side or just until beginning to brown. Remove to a platter and repeat cooking chicken pieces in batches. (The chicken doesn't have to be cooked through.)
To the skillet add garlic, cooking for 1 minute or until fragrant. Next, add brown sugar, apple juice, chicken stock, soy sauce, ketchup, brown sugar, bourbon, vinegar, onion powder, ginger and red pepper flakes. (You can use water, apple juice or additional chicken stock in place of bourbon.) Stir to combine.
Add chicken back to skillet, stir to coat with the sauce. Reduce heat to medium-low and let simmer uncovered for 15-20 minutes or just until chicken is cooked through and sauce has slightly thickened.
Serve immediately over fluffy rice garnished with green onion.
How To Thicken Sauce at the End of Cooking: In a small bowl dissolve 1-2 Tablespoons of cornstarch in 1-2 Tablespoons of cold water. Stir until completely dissolved. Increase heat, and stir the cornstarch slurry into the sauce. (Do not add it to the pan with undissolved clumps or the sauce will be lumpy.)Stir well, cook just until sauce has thickened slightly. Repeat process, if desired, until thickened to your taste. (You can opt to skip this step altogether.)