In a large bowl, whisk together soy sauce, brown sugar, minced garlic, and apple juice (or bourbon) until well combined. Add the chicken thighs, ensuring they are fully coated in the marinade. Cover and marinate for at least 30 minutes.

Heat vegetable oil in a large skillet over medium heat. Add the marinated chicken thighs and cook for 5-7 minutes on each side until golden brown and cooked through.

Remove chicken and pour reserved marinade into the skillet, scraping up brown bits. Bring to a gentle simmer for 2-3 minutes.

Mix cornstarch with cold water in a small bowl, add to the sauce while stirring continuously. Cook until thickened, about 2-3 minutes.

Return chicken to skillet, tossing to coat in sauce. Heat through for 1-2 minutes and serve over rice or with vegetables.