Step 1

Preheat oven to 350˚F. (for toasting chiles, see recipe note #1)

Step 2

Place chuck roast and short ribs in a large slow cooker and season evenly with pepper, oregano, cumin, coriander and 1 teaspoon of the salt. Pour beef broth and 2 tablespoons of the vinegar over meat. Cook on low 6-8 hours, or until beef is pull apart tender. While the beef begins to cook, move on to the next step (you'll be adding this mixture to the slow cooker as soon as possible).

Step 3

Clean Guajillo and Ancho chiles with a clean, damp cloth or damp paper towel. With kitchen scissors, cut off and discard the stems and shake out and discard any loose seeds. Arrange chiles on a baking sheet in a single layer and place in preheated oven. Toast chiles until puffed and fragrant, 5 to 6 minutes. Remove from oven and let cool slightly. With kitchen scissors, cut each chile lengthwise and remove and discard remaining seeds. (It's okay if the chiles break into small pieces - you'll be blending them anyway.)

Step 4

Transfer toasted chiles to a medium saucepan. Add onion, garlic, remaining 2 tablespoon of vinegar, remaining teaspoon of salt and enough water to cover (about 3 cups). Bring mixture to boil over medium-high heat. Reduce heat and cover; simmer 15 minutes. Remove from heat and allow to cool slightly.

Step 5

To make red chile sauce, transfer saucepan contents (including liquid) to blender and cover with a folded kitchen cloth (instead of the lid because the contents will be quite warm or use an immersion blender). Start to blend on the lowest setting and gradually increase the speed; blend until smooth. Taste for seasoning and add more salt if desired.

Step 6

Remove slow cooker lid and pour red chile sauce through a fine mash strainer over beef, use wooden spoon to stir and press against strainer to extract as much liquid from mixture as possible. Discard solids left in strainer. Add bay leaves and stir well to combine. Cover slow cooker and continue cooking beef until fall apart tender. (5 hours or more should remain.) Discard bay leaves and allow to cool slightly.

Step 7

When the meat has cooled slightly, carefully transfer from the braising liquid to a large bowl. Shred the meat using two forks, discarding any large chunks of fat.

Step 8

Skim fat off of the slow cooker juices.

Step 9

To serve as a stew, serve shredded meat with broth in bowls. Garnish with finely chopped white onion, chopped cilantro and lime wedges if desired. (See recipe notes and post above for other serving suggestions.)