Heat a large stainless skillet over medium-high heat.

Meanwhile season the whole roast with kosher salt and freshly ground black pepper.

Add the oil to the pan and swirl to coat and sear the roast on all sides for 4 to 6 minutes per side.

Transfer the seared roast to your slow cooker.

Reduce the heat under the pan and add in the onions with a pinch of kosher salt, cooking until tender while scraping up the browned bits on the bottom of the pan. Add a splash or two of water (up to 1/4 cup) to help scrape up those browned bits, simmer until any water evaporates. Transfer the onions to the slow cooker as well.

Meanwhile, in a large measuring cup, whisk together the brown sugar, garlic, tomato paste, chili powder, chipotle powder, smoked paprika and broth. Pour this overtop of the roast and onions.

Replace the cove to the slow cooker and cook on low for 6 to 8 hours or on high for 4 to 6 hours.

Once cooked, remove the roast to a cutting board and use two forks to shred. Transfer the shredded barbacoa back to the slow cooker and increase the heat to high and simmer for an additional 25 to 30 minutes.

Season with kosher salt, as needed.

Alternatively (if making in advance) transfer the shredded beef barbacoa to a container. And the liquids in a separate container and once cooled refrigerate overnight. Remove the top layer of fat and reheat the liquids and beef back in the slow cooker on low until heated through.