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 is dissolved and the mixture is well combined.
02 - Place the chicken breasts in a large resealable plastic bag or shallow dish. Pour the marinade over the chicken, ensuring each piece is evenly coated. Seal the bag or cover the dish and refrigerate for at least 30 minutes, or up to 4 hours for optimal flavor penetration.
03 - Preheat your grill to medium-high heat (approximately 375°F to 400°F). Lightly oil the grill grates to prevent sticking.
04 - Remove the chicken from the marinade, allowing any excess to drip off. Discard the remaining marinade. Place the chicken on the grill and cook for 5 to 7 minutes per side, or until the internal temperature reaches 165°F. Avoid pressing down on the chicken while grilling to retain juiciness.
05 - While the chicken is cooking, place the pineapple rings on the grill. Cook for 2 to 3 minutes per side until lightly charred with distinct grill marks and caramelized edges.
06 - Transfer the grilled chicken to serving plates and top each breast with grilled pineapple rings. Garnish with thinly sliced green onions and a sprinkle of sesame seeds if desired. Serve immediately.