Mix together the beef, egg, breadcrumbs, seasonings and worcestershire sauce. Add extra breadcrumbs if it needs it to bind well.
Form patties (you should get 6) and flatten as thin as you'd like (thinner cooks quicker), and dip very lightly in flour.
Heat the oil in a skillet, and cook the patties until browned (not necessarily cooked all the way through). Remove to a plate.
Gravy
Add the sliced onions to the skillet, and cook until translucent.
Add the flour to the onions, and mix, then blend in the beef broth, scraping the pan to get all the brown bits off the bottom. Cook (stirring) over low-ish heat until thickened.
Test for seasoning, and add salt/pepper if necessary.
Add the patties back to the pan with the gravy, and simmer until cooked through (maybe about 5 -10 minutes, depending on thickness of the patties)