Combine pineapple juice, brown sugar, soy sauce, rice vinegar, toasted sesame oil, freshly grated ginger, minced garlic, half of the sliced green onions, kosher salt, black pepper, and Sriracha (if using) in a bowl, stirring until the brown sugar dissolves completely. This Hawaiian-inspired marinade builds deep umami flavors through the combination of soy, ginger, and garlic. Place the beef short ribs in a large resealable bag or shallow dish and pour the marinade over them, ensuring all ribs are fully submerged and coated. Refrigerate overnight (or at least 8 hours) to allow the flavors to penetrate the meat—I find that marinating overnight makes a noticeable difference in tenderness and flavor development, so don't rush this step.

While the ribs marinate (or about 30 minutes before grilling), peel and slice the fresh pineapple into 1/2-inch thick rounds. Pat the pineapple slices dry with paper towels to remove excess moisture, which helps them caramelize rather than steam on the grill. Arrange the slices on a plate and lightly brush both sides with olive oil, then sprinkle with a pinch of kosher salt. This preparation ensures beautiful char marks and concentrates the natural sweetness of the pineapple.

Preheat your grill to high heat (around 450-500°F for a charcoal grill, or high setting for gas), allowing it to heat for at least 10-15 minutes until you see consistent flames or coals are ashy and glowing. Remove the marinated short ribs from the refrigerator about 15 minutes before grilling to bring them closer to room temperature for more even cooking. Pat the ribs dry with paper towels before placing them on the grill—this helps develop a better char and crust. Reserve the remaining marinade in a small bowl for basting, if desired.

Place the marinated short ribs directly on the hot grill grates in a single layer. For flanken-style ribs (typically thinner cut, about 1/2-inch thick), grill for 2 minutes per side over high heat to develop a caramelized crust while keeping the interior juicy and tender. If your ribs are thicker (closer to 3/4-inch or more), extend cooking to 4-5 minutes per side. Simultaneously, place the prepared pineapple slices on the grill at the same time as the ribs—they'll cook at a similar pace. I like to rotate both the ribs and pineapple halfway through each side to create attractive crosshatch char marks and ensure even caramelization.

Remove the grilled short ribs from the heat and transfer them to a warm plate or cutting board. Cover loosely with foil and let them rest for 5 minutes—this allows the juices to redistribute throughout the meat, keeping each bite tender and succulent. Remove the caramelized pineapple slices from the grill and arrange them on a serving platter. Once the ribs have rested, arrange them alongside or on top of the grilled pineapple. Garnish with the reserved fresh green onions from the marinade and sprinkle toasted sesame seeds over the top for a final touch of nutty flavor and visual appeal.