Pat the roast dry then lightly coat with salt and pepper. Brown the roast on all sides on a hot stove, then transfer to the slow cooker.
Add the rest of the ingredients to the slow cooker, then cover and cook until the meat is tender, about 6 to 8 hours on low.
If you'd like the sauce a bit thicker, combine 2 tbs cornstarch and 2 tbs water. Stir that into the slow cooker, and let cook uncovered for about 5 minutes.