Mix together the onion, breadcrumbs, egg and Worcestershire sauce, then season. Leave for 1 minute for the flavours to absorb, then add the beef mince and combine.
Rub a little oil on your hands and divide the mixture into 4 balls. Roll each ball, gradually flattening it while pressing in the edges so they're even. They should be about 10cm (4in) in diameter and (½ inch) thick.
Place the burgers between 2 sheets of nonstick baking paper and put in the fridge for at least 20 minutes to help the mixture bind together.
Grill or fry for 4-5 minutes each side, then serve in baps with lettuce and slices of tomato and red onion.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.