Pat the beef shanks dry with paper towels and sprinkle both sides with salt and black pepper.
Heat the olive oil in the slow cooker on the sear setting (or sear the beef shank in a pan on the stove). Sear both sides of the beef and move to a plate.
Place the potatoes and carrots on the bottom of the slow cooker.
Add the beef shanks back in trying not to layer them.
Place the mushrooms, onions, garlic, rosemary and thyme on top. Sprinkle the salt and pepper over everything.
Pour the beef bone broth and balsamic vinegar over the top of everything.
Cover and cook on the low setting for 9-10 hours.
Enjoy!