Season roast with salt and pepper on all sides.
Heat skillet over high heat and add butter and oil. Once the skillet is very hot, carefully add the beef roast. Sear on all sides for about 30 seconds until you have a nice crust. Transfer seared roast to your slow cooker.
In the same skillet you cooked the roast, add remaining ingredients (except for the cornstarch) and bring to a simmer. Simmer for about 5-10 minutes.
Carefully pour red wine sauce over the beef roast.
Cook in your slow cooker on the low setting for 7-8 hours or on high setting for 4 hours.
When done, transfer beef roast to a plate. To thicken the sauce, pour 1 cup of the sauce into a bowl and whisk in a tablespoon of cornstarch. Pour sauce back into the slow cooker and stir to combine.
Pour sauce over roast and serve with your favorite side dishes. Enjoy!