Heat the olive oil in a pan and cook the onions on a medium heat until soft and transparent in colour.
When cooked, place in a bowl along with all the ingredients and mix well.
Leave to rest in the fridge for 1 hour, then using your hands, shape onto burgers and place onto a slightly oiled tray.
Either grill, oven roast or panfry the beef burgers until cooked through.
Serve with crisp green salad and a crusty roll.