Squeeze the bread almost dry, put it in a large bowl and mash with a fork. Add the beef, onion, egg, salt and pepper and mix together lightly. Divide the mixture into six equal portions, shape into patties and dust with the seasoned flour.
In a large frying pan, heat enough dripping or oil to come halfway up the patties and fry the patties for about 4 minutes on each side, or until cooked through. Drain on paper towels.
Serve the patties on the toasted buns with the tomato and beetroot slices and lettuce leaves. You can spark up your hamburgers with other additions, such as fried onions, sliced Cheddar cheese, pickled cucumbers, a fried egg, fried bacon, mayonnaise and barbecue sauce. Don't be afraid to ring the changes on your burgers, just don't make them so high that they're difficult to eat.