In a mixing bowl, whisk together pineapple juice, soy sauce, brown sugar, ginger, garlic, and rice vinegar. Reserve half of the marinade for later use. Add the chicken thighs and coat well. Marinate for 30 minutes.

Heat oil in a skillets over medium-high heat. Remove chicken from marinade and sear for 5-6 minutes on each side until golden.

In a saucepan, bring reserved marinade to a boil, then simmer until reduced by half. Mix cornstarch with water to create a slurry and stir into the marinade until thickened.

Pour the thickened glaze over the seared chicken and cook for about 1 minute to allow it to caramelize.

Remove from heat and let the chicken rest for 5 minutes before slicing and serving. Garnish with sesame seeds and chopped green onions.