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 or grill pan to medium-high heat. Lightly oil the grates to prevent sticking.
04 - Remove the chicken from the marinade and grill for 6 to 7 minutes per side, until fully cooked through with clear grill marks. During the last 2 minutes, place a slice of cheese on each breast and allow it to melt.
05 - Grill the pineapple rings for 1 to 2 minutes per side until lightly charred and caramelized. Set aside.
06 - While the chicken cooks, spread butter on the cut sides of each bun. Grill or toast until golden brown, about 1 to 2 minutes.
07 - Spread mayonnaise on the bottom halves of the toasted buns. Add Sriracha or hot sauce if desired for a spicy kick.
08 - Layer each sandwich starting with a lettuce leaf, followed by the cheesy grilled chicken, a grilled pineapple ring, a tomato slice, and red onion. Cap with the top bun and serve immediately.