Add onions, carrots, steak, mushrooms, and red potatoes into the slow cooker.
Whisk together balsamic vinegar, honey, beef broth, Worcestershire sauce, and salt. Pour over steak and veggies. Add in rosemary sprigs, if using. Cover and cook on Low for 6-8 hours, stirring halfway through cook time (if possible).
Enjoy! (Leftovers are delicious, too!)
Recipe from Living Well Kitchen https://blog.memeinge.com/slow-cooker-honey-balsamic-steak-and-veggies/