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, approximately 400°F. Lightly oil the grates to prevent sticking.
03 - Remove the chicken from the marinade, letting excess drip off. Grill the breasts for 6 to 7 minutes per side, until the internal temperature reaches 165°F and prominent grill marks form. During the final 2 minutes, place a slice of cheese on each breast and close the lid to melt.
04 - Place the pineapple rings directly on the grill and cook for 1 to 2 minutes per side until lightly charred with caramelized edges. Remove and set aside.
05 - While the chicken rests, spread butter on the cut sides of each bun. Grill or toast face-down for 1 to 2 minutes until golden brown and crisp.
06 - Spread mayonnaise on the bottom half of each toasted bun. 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 and melted cheese, a grilled pineapple ring, a tomato slice, and a few rings of thinly sliced red onion. Cap with the top bun.
08 - Serve the sandwiches immediately while warm, alongside your choice of side dishes.