How to Make It
Preheat the oven to 325°. In a mortar, pound the dried chiles until finely ground. In a large enameled cast-iron casserole, heat the olive oil. Season the beef shank generously with salt and pepper. Add the shank to the casserole and cook over moderately high heat until browned on all sides, about 25 minutes. Transfer the shank to a plate.
Add the onion, garlic and a generous pinch of salt to the casserole and cook over moderately high heat, stirring occasionally, until the onion is beginning to brown, about 8 minutes. Add the ground chiles, oregano and cumin and cook, stirring, until fragrant, about 1 minute. Add the beer and bring to a boil, scraping up any browned bits with a wooden spoon. Cook until the beer is reduced by one-half, about 6 minutes. Add the crushed tomatoes and chicken stock and return to a boil. Return the shank and any accumulated juices to the casserole. Cover and braise in the oven for about 3 1/2 hours, basting the shank with sauce every hour, until the meat is very tender. Remove the casserole from the oven and let the beef shank stand at room temperature in the braising liquid, uncovered, until ready to grill, at least 2 hours.
In a medium bowl, whisk the red wine vinegar with the sugar and salt until the sugar is dissolved. Add the sliced onion, cover and let stand at room temperature, stirring occasionally, for at least 1 hour.
In a small bowl, whisk all of the ingredients together and season with salt and pepper. Refrigerate until ready to serve.
In a large bowl, whisk the mayonnaise with the hot sauce and season with salt and pepper. Add the red cabbage and toss to coat. Refrigerate until ready to serve.
Carefully remove the cooled shank from the braising liquid and transfer to a plate. Transfer the braising liquid to a medium saucepan and bring to a simmer over low heat, skimming off any accumulated fat. Stir in the cider vinegar and butter and season with salt and pepper; keep warm.
Meanwhile, light a grill. Fold a 24-inch sheet of foil in half and brush lightly with canola oil. Set the foil oiled side up on the grill. Place the cooled shank on the foil, cover and grill over moderately high heat, basting with the warm braising liquid every 10 minutes, until the shank is lightly charred and warmed through, 35 to 40 minutes. Transfer the shank to a platter and let rest for 10 minutes. Discard the strings and serve the shank warm with the pickled red onion, lime crema, cabbage slaw, warm flour tortillas, chopped cilantro, lime wedges and the remaining braising liquid. Set out tongs or a fork so guests can pull the meat themselves.