▢½ cup soy sauce
▢½ cup brown sugar
▢½ cup pineapple juice
▢2 cloves garlic minced
▢¼ teaspoon ginger
▢1 Tablespoon rice vinegar
▢½ teaspoon kosher salt
▢¼ teaspoon pepper
▢½ teaspoon sesame oil optional
▢1 Tablespoon sesame seeds optional
▢1 Tablespoon cornstarch
▢2 Tablespoons cold water
▢2 pounds boneless skinless chicken breasts cut into 1-inch cubes
▢1 red bell pepper cut into 1-inch cubes
▢1 yellow bell pepper cut into 1-inch cubes
▢1 green bell pepper cut into 1-inch cubes
▢1 red onion cut into 1-inch cubes
▢2 cups fresh pineapple cut into 1-inch cubes
▢Metal or wooden skewers soaked in water for 1 hour
Combine the soy sauce, brown sugar, pineapple juice, garlic, ginger, rice vinegar, salt, pepper, and sesame oil and seeds, if using. Whisk well, then transfer ½ cup to a large ziploc bag to use as a marinade.
Pour the remaining sauce into a small saucepan and heat over medium-high heat until it begins to boil. Combine the cornstarch and water in a small bowl, mixing with a fork to create a slurry, then pour into the boiling sauce, stirring and cooking for about 1 minute until thickened. Set aside to cool until ready to use.
Add chicken to the bag containing the reserved marinade and let it sit in the fridge for at least 30 minutes.
Preheat grill to medium-high heat. Thread chicken, peppers, onion, and pineapple onto soaked skewers, then grill over direct heat for 8 to 10 minutes, turning partway through to grill evenly on both sides, until chicken is cooked through and reaches 165 degrees F when tested with an instant read meat thermometer.
Brush with the thickened teriyaki sauce and serve with any remaining sauce for dipping.