01 - In a mixing bowl, whisk together the teriyaki sauce, soy sauce, pineapple juice, olive oil, garlic powder, and black pepper until well combined. Add the chicken breasts, turning to coat evenly. Cover and refrigerate for at least 30 minutes or up to 2 hours for deeper flavor.
02 - Preheat your grill or grill pan to medium-high heat. Lightly oil the grates to prevent sticking.
03 - Remove the chicken from the marinade, letting excess drip off. Place the chicken breasts on the grill and cook for 6 to 7 minutes per side, or until fully cooked through with distinct grill marks. During the last 2 minutes of grilling, lay a slice of cheese atop each breast and allow it to melt.
04 - Place the pineapple rings on the grill and cook for 1 to 2 minutes per side until lightly charred and caramelized. Remove and set aside.
05 - While the chicken grills, spread butter on the cut sides of each bun. Place the buns cut-side down on the grill and toast until golden brown, about 1 minute.
06 - Spread mayonnaise on the bottom halves of the toasted buns. Add Sriracha or hot sauce if desired for a spicy kick.
07 - Layer each bottom bun with a lettuce leaf, followed by the grilled chicken breast with melted cheese, a grilled pineapple ring, a tomato slice, and several slices of red onion. Cap with the top bun.
08 - Serve the sandwiches immediately while warm, paired with your favorite side dishes.