Pull the meat off the bones and keep it in the fridge for up to several days, ready for the most glorious tacos you’ve ever made: Mince white onion and lots of fresh cilantro together on a cutting board or in a mini food processor. Heat the short rib meat in a skillet over medium-high heat, turning with a thin metal spatula, until crisp and deeply browned, about 2 minutes (it doesn’t take long), adding a pinch or so of ground cumin and cayenne. Warm corn tortillas and fill them with crisp meat and the onion-cilantro mixture, with lime wedges for squeezing.