In the bowl of a food processor, finely chop the pear, scallions, and garlic. Add the remaining marinade ingredients. Process until well combined.
Divide the ribs and marinade among two large, resealable plastic bags. Press the air out of the bags and seal tightly. Turn the bags to distribute the marinade, place in a large bowl, and refrigerate for 2 to 4 hours, turning occasionally. Remove the ribs from the refrigerator and let stand at room temperature for 15 to 30 minutes before grilling.
Prepare the grill for direct cooking over high heat (230° to 290°C).
Prepare the grill for cooking over high heat (260°C).
Brush the cooking grates clean. One at time, lift the ribs and let the liquid and solid bits fall back into the bag or bowl. Discard the marinade. Grill the ribs over direct high heat, with the lid open for a charcoal grill but closed for a gas grill, until they are nicely charred on both sides and cooked to medium rare, 3 to 5 minutes, turning occasionally. Remove from the grill and top with the sesame seeds.
Brush the cooking grates clean. One at time, lift the ribs and let the liquid and solid bits fall back into the bag or bowl. Discard the marinade. Grill the ribs over high heat, with the lid open for a charcoal grill but closed for a gas grill, until they are nicely charred on both sides and cooked to medium rare, 3 to 5 minutes, turning occasionally. Remove from the grill and top with the sesame seeds.
