Add the cubed beef into the pot and turn the heat up slightly to medium-high and cook until the beef is browned and cooked through, about 10 minutes. Take the beef out and set it to the side.
If there is not enough rendered bacon or meat fat in the pot then add in the optional olive oil and over low heat caramelize the onions and leeks for 30-35 minutes. Stir occasionally.
Add in the garlic and cook for 1 to 2 minutes before adding back in the beef, bacon, carrots, celery, parsnips, turnips, bay leaves, and beef stock and cook over low to medium heat for 60 minutes.