Marinate the Chicken: In a mixing bowl, combine ¼ cup soy sauce, 3 tablespoons pineapple juice, 2 tablespoons sesame oil, 2 cloves minced garlic, 1 teaspoon grated ginger, and 2 tablespoons brown sugar. Whisk the marinade until well-combined. Add the chicken to the bowl, ensuring each piece is coated thoroughly. Cover and refrigerate for at least 30 minutes, preferably for 2-4 hours for maximum flavor., Cook the Chicken: Preheat your grill or skillet on medium-high heat. Remove the chicken from the marinade, letting excess liquid drip off. Season with salt and pepper. Grill the chicken for about 6-7 minutes per side, or until the internal temperature reaches 165°F (75°C). If pan-searing, cook until both sides are golden brown and fully cooked. Remove from heat and let it rest for 5 minutes before slicing., Garnish: Slice the chicken and sprinkle with sliced scallions and sesame seeds, if using., Rinse the Rice: Place 1 cup of jasmine rice in a fine-mesh strainer and rinse under cold water until the water runs clear., Cook the Rice: In a saucepan, combine the rinsed rice, 1 can of coconut milk, 1 cup of water, and ½ teaspoon salt. Stir well to mix. Bring the mixture to a boil over medium-high heat. Once boiling, lower the heat, cover with a lid, and simmer for 15-20 minutes, or until the rice is tender and has absorbed liquids. Remove from heat and let it sit, covered, for an additional 5 minutes. Fluff the rice gently with a fork before serving.