Prepare Marinade: In a large mixing bowl, whisk together pineapple juice, soy sauce, brown sugar, vegetable oil, minced garlic, ginger, and black pepper until the brown sugar has completely dissolved.

Marinate Chicken: Add the boneless, skinless chicken breasts to the marinade, ensuring they are thoroughly coated. Cover and refrigerate for at least 1 hour.

Preheat Grill: Preheat your grill or grill pan to medium-high heat.

Grill Chicken: Remove chicken from marinade and grill for about 6-7 minutes per side, until cooked through.

Prepare Coconut Rice: In a saucepan, combine jasmine rice, coconut milk, water, and salt. Bring to a boil, then lower heat, cover, and simmer for 15-20 minutes.

Fluff Rice: After cooking, let the rice sit covered for 5 minutes, then fluff with a fork.

Serve: Slice the grilled chicken and plate it alongside coconut rice. Garnish with chopped green onions and sesame seeds.