Blend 6 cups water, the brown sugar, soy sauce, garlic
, onion and pear in a blender
, in batches if needed, until well blended.
Lay the short ribs in a baking dish and pour the marinade over. Marinate in the refrigerator for 24 hours.
Preheat the grill to high heat.
Grill the short ribs for 2 minutes per side, and then serve garnished with the scallions.