01 - In a medium bowl, whisk together the soy sauce, pineapple juice, brown sugar, olive oil, minced garlic, grated ginger, and black pepper until the sugar dissolves and the mixture is well combined.
02 - Place chicken breasts in a large resealable plastic bag or shallow dish. Pour the marinade over the chicken, ensuring each piece is evenly coated. Seal and refrigerate for at least 30 minutes, or up to 4 hours for deeper flavor penetration.
03 - Preheat an outdoor grill or grill pan to medium-high heat (approximately 400°F). Lightly oil the grill grates to prevent sticking.
04 - Remove chicken from the marinade, allowing excess liquid to drip off. Discard remaining marinade. Grill the chicken for 5 to 7 minutes per side, or until the internal temperature reaches 165°F when measured with a meat thermometer.
05 - While the chicken cooks, place the pineapple rings on the grill. Cook for 2 to 3 minutes per side until grill marks appear and the pineapple is lightly caramelized.
06 - Transfer the grilled chicken to a serving platter and top with the charred pineapple rings. Garnish with sliced green onions and sesame seeds if desired. Serve immediately.