Step 1: In a large bowl, whisk together all marinade ingredients (soy sauce, ketchup, brown sugar, pineapple juice, Worcestershire, vinegar, garlic, ginger, paprika) until the sugar dissolves.

Step 2: Pro Tip: Reserve about ¾ cup of the marinade in a separate jar/container and refrigerate. This will be your clean "basting sauce" later.

Step 3: Place the chicken thighs in a large dish or ziplock bag. Pour the remaining marinade over the chicken, ensuring it's fully coated. Seal and marinate in the refrigerator for at least 4 hours, or ideally overnight.

Step 4: Preheat your grill to medium-high heat (approx. 375-400°F / 190-200°C). Clean and oil the grates.

Step 5: Remove chicken from the marinade (let excess drip off) and discard the used marinade. Place chicken on the hot grill.

Step 6: Grill for 6-7 minutes per side, until well-marked. In the last 5 minutes, begin basting generously with the reserved clean marinade. Turn and baste frequently to build a glaze.

Step 7: Chicken is done when an internal thermometer reads 165°F (74°C) for breasts or 175°F (79°C) for thighs.

Step 8: Remove chicken from the grill and let it rest for 5-10 minutes.

Step 9: While chicken rests, grill the pineapple rings for 1-2 minutes per side until caramelized.

Step 10: Serve the grilled chicken over rice with a grilled pineapple ring. Garnish with sliced green onions and a sprinkle of sesame seeds.