Preheat oven to 300 degrees F. Trim the large pieces of fat from beef. Cut into 3 inch chunks and allow to reach room temperature. Season generously with salt and pepper.
Heat the dutch oven to medium high heat. Add enough vegetable or canola oil to coat the bottom of the pot. You can also use a slow cooker or Instapot.
Add the chunks of beef and sear for about 3 minutes per side. You might have to do a few batches so you don’t overcrowd the pan. When seared on both sides, remove from the pan and place to the side.
Turn off the heat and add all the pieces of beef back to the pot. Add the beef stock, bay leaves, cumin and the entire bottle of the Serious Foodie Mexican BBQ Sauce. Turn heat to medium high and bring to boil. Place pot in oven with lid on and cook for 6 hours. If using a slow cooker or Insta-pot, place on low.
Remove the beef from the pan and place in a roasting pan. Using two forks, shred the meat by pulling the forks in opposite directions. Season the meat with salt to taste. We like to de-fat the liquid in the pot by placing it in a tall container, put in the refrigerator for a few hours, and just skim off the top. Adding the beef back into the cooking liquid for a few hours, or overnight, makes for very flavorful meat.
To assemble the tacos: add a healthy amount of queso fresco, chopped cilantro, diced onion (or pickled onion), and sliced radishes