01 - Whisk together soy sauce, pineapple juice, olive oil, garlic powder, and black pepper in a bowl. Submerge chicken breasts in the mixture and let marinate for 15 minutes to 2 hours, depending on preferred intensity.
02 - Combine soy sauce, pineapple juice, brown sugar, and rice vinegar in a small saucepan over medium heat. Bring to a gentle simmer, then stir in the cornstarch slurry. Cook for 1 to 2 minutes until the sauce coats the back of a spoon. Remove from heat and set aside.
03 - Preheat grill or grill pan to medium-high temperature, approximately 375°F to 400°F.
04 - Place marinated chicken on the grill and cook for 5 to 6 minutes per side until internal temperature reaches 165°F. During the final 2 minutes of cooking, add pineapple rings to the grill and cook until lightly caramelized with grill marks.
05 - Lightly toast burger buns on the grill for 30 to 60 seconds until golden brown and warmed through.
06 - Spread mayonnaise on the bottom bun if desired. Layer lettuce, grilled chicken breast, and drizzle with teriyaki sauce. Add grilled pineapple ring, tomato slice, red onion, and crown with the top bun.
07 - Serve immediately while chicken is hot and pineapple retains its sweetness. Pair with sweet potato fries or crisp salad if desired.