How to Make It
In a large resealable plastic bag, mix the onion with the soy sauce, ginger, sugar, garlic and 1 teaspoon each of salt and pepper. Add the short ribs, seal the bag and turn to coat all the ribs well. Let marinate in the refrigerator for at least 2 hours or overnight.
Light a grill. Scrape some of the marinade off the meat. Season the ribs with salt and pepper. Grill over high heat, turning once, until lightly charred in spots, about 5 minutes total. Transfer to a platter and let rest for 2 minutes. Use scissors to snip off the bones and cut the meat into bite-size pieces. Serve in tortillas with hoisin sauce, julienned cucumbers, grilled yellow squash, sliced chiles and scallions, and lime wedges for squeezing.