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 blended.
02 - Place the chicken breasts in a large resealable plastic bag or shallow dish. Pour the marinade over the chicken, sealing and turning to coat each piece evenly. 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. Lightly oil the grates with cooking oil to prevent sticking.
04 - Remove the chicken from the marinade, allowing excess to drip off. Discard the remaining marinade. Grill the chicken for 5 to 7 minutes per side, or until the internal temperature registers 165°F (74°C) and the juices run clear.
05 - While the chicken cooks, place the pineapple rings on the grill. Cook for 2 to 3 minutes per side until lightly charred with visible grill marks. Remove and set aside.
06 - Transfer the grilled chicken to a serving platter. Top each breast with a grilled pineapple ring and garnish with sliced green onions and sesame seeds. Serve immediately with coconut rice and a crisp green salad if desired.