Heat the olive oil in a skillet over medium heat. Add the beef stew meat and brown it on all sides for a few minutes.
Transfer the browned beef to the slow cooker.
Add the diced onion, minced garlic, green beans, beef broth, rosemary, salt, and pepper to the slow cooker.
Stir everything together until the ingredients are evenly distributed.
Cover and cook on low for 7 hours until the beef is tender.
Stir once more before serving.