01 - In a mixing bowl, whisk together the teriyaki sauce, soy sauce, pineapple juice, olive oil, garlic powder, and black pepper until well combined.
02 - Add the chicken breasts to the marinade, turning to coat evenly. Cover and refrigerate for at least 30 minutes, or up to 2 hours for deeper flavor.
03 - Preheat your grill to medium-high heat (approximately 375–400°F). Lightly oil the grates to prevent sticking.
04 - Remove chicken from the marinade, letting excess drip off. Grill the breasts for 6 to 7 minutes per side until fully cooked through (internal temperature of 165°F) and distinct grill marks form. During the final 2 minutes, place a slice of cheese on each breast and close the lid to melt.
05 - Place the pineapple rings on the grill and cook for 1 to 2 minutes per side until lightly charred with visible caramelization. Remove and set aside.
06 - While the chicken finishes, spread butter on the cut sides of each bun. Place them cut-side down on the grill and toast until golden brown, about 1 minute.
07 - Spread mayonnaise on the bottom and top halves of each toasted bun. Add Sriracha or hot sauce if desired for a spicy kick.
08 - Layer each bottom bun with a lettuce leaf, followed by the grilled chicken with melted cheese, a grilled pineapple ring, a tomato slice, and a few rings of red onion. Cap with the top bun and serve immediately.