Heat the olive oil in a large skillet over medium-high heat. Add the beef stew meat and brown on all sides for about 5 minutes.
Transfer the browned beef to the slow cooker.
Add the chopped cabbage, parsnip chunks, sliced leeks, carrot slices, potato cubes, and minced garlic to the slow cooker.
Pour in the beef broth. Sprinkle the dried thyme, salt, and black pepper over the top, then tuck in the bay leaves.
Stir gently to combine everything. Cover and cook on low for 8 hours.
Remove the bay leaves before serving.