Prepare the Marinade: In a medium bowl, whisk together 1 cup of pineapple juice, ½ cup soy sauce, ¼ cup brown sugar, 2 tablespoons honey, 2 tablespoons rice vinegar, 2 tablespoons sesame oil, 3 cloves minced garlic, 1 tablespoon grated ginger, and optional crushed red pepper flakes.

Marinate the Chicken: Place 2 pounds of boneless, skinless chicken thighs in a resealable plastic bag. Pour half of your marinade over the chicken, seal the bag, and refrigerate for at least 2 hours or overnight.

Cook the Chicken: Preheat your grill to medium-high heat (around 400°F). Grill the chicken thighs for 5-7 minutes on each side until cooked through.

Make the Sauce: Pour the reserved marinade into a saucepan. Boil then simmer, optionally thickening with 1 tablespoon of cornstarch mixed with 2 tablespoons of water.

Serve: Drizzle the thickened teriyaki sauce over the grilled chicken, garnish with green onions and sesame seeds, and serve with steamed rice or stir-fried vegetables.