Tangy-sweet pulled beef on a bun is easy to make and great for serving a crowd; it makes a large batch, but leftovers freeze very well.
In a heavy skillet, heat a drizzle of oil over medium-high heat and brown the roast on all sides, seasoning it with salt and pepper.
Place the onions in the bottom of a slow cooker and set the beef on top.
Add the remaining ingredients, cover and cook on low for 6-8 hours.
Pull the meat apart with two forks, tossing with the juices in the bottom of the slow cooker.
Add extra barbecue sauce to taste, and serve on soft buns.