01 - Whisk together soy sauce, pineapple juice, olive oil, garlic powder, and black pepper in a bowl. Submerge chicken breasts in the marinade and refrigerate for at least 15 minutes, up to 2 hours for enhanced flavor.
02 - Combine soy sauce, pineapple juice, brown sugar, and rice vinegar in a small saucepan. Bring to a simmer over medium heat. Gradually whisk in the cornstarch slurry and cook for 1-2 minutes until sauce thickens noticeably. Remove from heat and set aside.
03 - Heat grill or grill pan to medium-high temperature, approximately 375-400°F.
04 - Cook marinated chicken breasts for 5-6 minutes per side until internal temperature reaches 165°F. During the final 2 minutes of cooking, place pineapple rings on the grill and cook until lightly caramelized with distinct grill marks.
05 - Lightly toast burger buns on the grill cut-side down for approximately 30-60 seconds until golden brown.
06 - Spread mayonnaise on the bottom bun if desired. Layer with lettuce leaf, grilled chicken breast, drizzle of teriyaki sauce, grilled pineapple ring, tomato slice, and red onion. Complete with top bun and serve promptly.