Heat olive oil in a large skillet over medium-high heat. While the oil is heating, generously season all sides of the chuck roast with kosher salt and freshly ground pepper.

When the oil starts to shimmer, carefully place the roast in the hot pan and sear it on all sides by letting it sit without moving for a minute or two on each side before flipping it. Searing won't take very long - you just want to quickly brown the roast to add flavor and seal in the juices.

Transfer the roast to your slow cooker. Sprinkle onion soup mix over the roast and add water and beef broth. Cook on high for 4-6 hours or on low for 8-10 hours.

When the meat is so tender that it shreds easily with a fork, remove the roast from the slow cooker and shred. Serve by piling the shredded meat onto sliced, crusty rolls with a slice of Swiss cheese. Toast the cheese and top bun under the broiler until the cheese melts and the bun starts toasting. Serve with the juices from the slow cooker as au jus for dipping.