Make the marinade: in a blender or food processor combine Soy Sauce, Water, Brown Sugar, peeled and chopped Korean Pear, quartered Onion, peeled Garlic, peeled Ginger, roughly chopped Scallions, Mirin, Toasted Sesame Oil and a good crack of Black Pepper. Blend until mostly smooth.
Put the Flanken-Cut Beef Short Ribs into a large bowl or resealable bag, pour the marinade over the meat so each piece is well coated, massage to distribute, then refrigerate for at least 4 hours or overnight for best flavor and tenderness.
When ready to cook, preheat a grill or heavy skillet until very hot. Remove the ribs from the fridge about 20–30 minutes before cooking so they lose some chill; shake off excess marinade (discard any used marinade).
Grill the ribs over direct high heat 3–4 minutes per side (depending on thickness) until nicely charred at the edges and cooked through, turning once or twice to develop a caramelized crust.
Transfer the cooked ribs to a cutting board and let rest for 5 minutes, then cut into individual pieces or bite-sized strips between the bones if needed.
Serve the galbi with a platter of Green Leaf Lettuce and Perilla leaves for wrapping, a small bowl of Ssamjang for dipping, and hot Cooked Short-Grain White Rice on the side.
Garnish the grilled ribs with a sprinkle of Toasted Sesame Seeds and some thinly sliced scallions (reserve a little scallion from the marinade step if you like) before serving; assemble lettuce wraps with rice, galbi and ssamjang for each bite.
