01 - Combine soy sauce, pineapple juice, olive oil, garlic powder, and black pepper in a bowl. Add chicken breasts and marinate for at least 15 minutes, up to 2 hours for enhanced flavor.
02 - In a small saucepan over medium heat, mix soy sauce, pineapple juice, brown sugar, and rice vinegar. Bring to a simmer, then stir in cornstarch slurry. Cook for 1-2 minutes until thickened. Set aside.
03 - Heat grill or grill pan to medium-high temperature.
04 - Cook marinated chicken breasts for 5-6 minutes per side until internal temperature reaches 165°F. During the final 2 minutes, grill pineapple rings until lightly caramelized.
05 - Lightly toast burger buns on the grill until golden.
06 - Spread mayonnaise on bottom bun if desired. Layer lettuce, grilled chicken, teriyaki sauce, pineapple ring, tomato, and red onion. Top with bun and serve immediately.