These crock pot beef tips are made with sirloin tips, mushrooms, and a tasty thickened sauce. Beef tips can be cut from any section, but sirloin tips or tenderloin tips are usually labeled. Budget-friendly chuck stew beef may be used as well. Red wine is optional in this recipe, but it does add some nice flavor. If you (or members of your family) aren't a fan of mushrooms, feel free to leave them out. I sometimes add a cup of frozen pearl onions to the crock pot along with the beef.