Start by preheating your Blackstone griddle over medium-high heat. Ensure the entire cooking surface is evenly heated before adding the ingredients.
Season the chicken pieces with salt, pepper, and any other desired spices or herbs. Set aside while you prepare the vegetables if using fresh vegetables. Wash and chop the vegetables into bite-sized pieces. Keep them separate and organized for easy cooking.
Pour a generous amount of high-heat cooking oil, such as vegetable or peanut oil, onto the griddle. Let the oil heat up until it shimmers.
Place the seasoned chicken pieces onto the hot griddle, spreading them out in a single layer. Allow the chicken to cook undisturbed for a few minutes until browned and cooked through. Flip the chicken pieces and cook for a few minutes until fully cooked. Remove the chicken from the griddle and set it aside.
Add a bit more oil to the griddle if needed, then add the chopped vegetables. Stir fry them quickly, tossing them with a spatula or tongs to ensure even cooking. Cook until the vegetables are tender-crisp, maintaining their vibrant colors. Return the cooked chicken to the griddle once the vegetables are cooked to your liking. Toss the chicken and vegetables together, allowing them to heat through, and combine flavors.
Pour the prepared stir-fry sauce over the chicken and vegetables on the griddle. Stir well to coat everything evenly in the sauce. Continue cooking for a minute or two to let the sauce thicken slightly and fully coat the ingredients.
Transfer the chicken stir fry from the griddle to a serving platter or individual plates. Garnish with optional extras like minced garlic, minced ginger, sliced scallions, or toasted sesame seeds. Serve hot, and enjoy!