Cut the chuck roast into 6 portions while removing any large pieces of fat. Heat 1 Tbsp vegetable oil in a skillet.
Dab the roast dry with paper towels, and season with salt and pepper (about 1 tsp salt and 3/4 tsp pepper). Add 3 pieces to the skillet and sear until browned on all sides. The Maillard reaction, which occurs during searing, creates hundreds of flavor compounds that are essential to the final flavor of the barbacoa. This reaction happens at temperatures between 285-392°F. Transfer the seared pieces to a slow cooker.
Add the remaining 1 Tbsp vegetable oil to the skillet and repeat the searing process with the remaining 3 roast pieces. Nestle the beef portions side by side in an even layer in the slow cooker.
In a food processor, pulse together chipotle chilies, garlic, and 1/4 cup beef broth until well pureed, occasionally stopping and scraping down the sides of the processor.
In a 2 cup liquid measuring cup or in a bowl, whisk together the remaining beef broth with the chipotle mixture, cumin, oregano, and cloves. Pour the mixture over the beef in the slow cooker, then nestle the bay leaves between the beef portions.
Cover and cook on low heat for 8 - 9 hours.
Remove the beef from the slow cooker, leaving the broth. Shred the beef. Stir the lime juice into the broth in the slow cooker, then return the beef to the slow cooker and cook on low or warm for 20 - 30 minutes longer.
Strain the liquid from the beef and serve in tortillas with desired toppings for the best barbacoa tacos.