Place beef, grated onion and Worcestershire in a large bowl with and season. Mix well.
Divide mince equally into 4. Wet hands and roll each portion into balls then flatten into patties.
Heat BBQ grill to high and cook patties for 3-4 minutes on each side, turning once. Remove patties and top with Swiss cheese and set aside. Grill bacon rashers and toast rolls.
Top each bun base lettuce, cheese topped beef pattie, bacon rasher and a good squeeze of caramilised onion mayonaise. Serve with pickles on the side.
