For an even richer flavor, sear the beef tips in a hot skillet with a little olive oil before adding them to the slow cooker. This will create a beautiful crust and enhance the depth of flavor. If you don't have beef bone broth, you can substitute with regular beef broth or stock. For a more intense mushroom flavor, consider using a combination of different mushroom varieties, such as cremini, shiitake, or oyster mushrooms. Serve these delectable beef tips and mushroom gravy over mashed potatoes, egg noodles, rice, or creamy polenta for a complete and comforting meal.