Heat the oil or butter in a casserole over medium heat. Add the onion, carrot, garlic and parsnip and cook and stir till the onion has softened. Add the steak and cook and stir till sealed on all sides.
Add the beef stock and seasoning. Bring to the boil, then reduce heat and gently simmer for about 2 hours, or until steak is tender.
Just before serving, add cornflour and stir well. Simmer till the gravy has thickened.