Preheat the oven to 350°F (180°C).
In a saucepan over high heat, bring the broth to a boil, then remove from the heat and add the ancho chiles. Set aside to steep.
Warm the olive oil in an ovenproof pot over medium-high heat. Pat the short ribs dry and season all over with salt and pepper. Working in batches, add the ribs to the pot and sear until browned on all sides, about 4 minutes per side. Transfer to a plate and set aside.
Add the yellow onion to the pot and cook, stirring often, until golden, about 4 minutes. Add the garlic, season with salt and pepper, and cook just until the garlic is soft, about 1 minute. Add the broth, chiles, and wine, stirring to scrape up any browned bits on the bottom of the pot. Nestle the ribs in the liquid, cover the pot, and transfer to the oven until the meat falls off the bones, 2 1/2 to 3 hours. Check the pot every 45 minutes or so to make sure there is enough liquid, adding more broth as needed; it should reach about 3/4 of the way up the sides of the ribs.
Using tongs, transfer the ribs and the chiles to a plate to cool. Set the pot with the cooking liquid aside to cool.
When the ribs are cool enough to handle, use your hands or 2 forks to shred the meat. Discard the bones. Using a large spoon, skim the fat off the top of the cooled liquid in the pot. Transfer the contents of the pot and 1 of the reserved chiles to a blender and process to a smooth purée. Taste and, if desired, add more chile and purée again. Otherwise discard the remaining chiles. Return the puréed sauce to the pot and bring to a boil over high heat to warm it through. If a thicker sauce is desired, cook until the sauce reduces by half, about 5 minutes. Add the shredded meat and cook just until warmed through, about 4 minutes.
To assemble the tacos, fill the tortillas with the meat (using about 3 to 4 tablespoons shredded meat per taco) and top with some drained pickled onions, a dollop of crema, and some cilantro. Serve right away.