Mix the beef mince, onion, breadcrumbs and egg in a large bowl.
Divide mince into 4 equal sized patties and place onto a plate. Cover with plastic wrap and pop into the fridge for 30 minutes or until you're ready to barbecue the patties.
Place the beef patties on a barbecue grill to cook. Turn the patties over once during cooking.Set aside when cooked to your liking.
Cook the bacon on the barbecue, turning after a couple of minutes. Remove when crispy and set aside.
Meanwhile, prepare the salad ingredients and place on a platter to serve.
Serve rolls with 2 slices of bacon, a beef patty and your choice of salad ingredients. Top with barbecue sauce.