Place beef, zucchini and herb mix in a bowl. Season with salt and pepper. Mix well to combine. Divide mixture into 3 even portions and shape each portion into a 1.5cm thick, 10cm diameter patty. Using a 5cm diameter cup or cutter, cut the centre from each patty. Use the cut-out mince to form a 10cm ring for your fourth patty

Heat an oiled barbecue plate (with hood) over medium-high heat. Place onion to one side of the flat plate. Barbecue, turning occasionally, for 5-7 minutes or until golden. Transfer to a bowl.

Meanwhile, place patties on flat plate. Barbecue for 3-4 minutes or until base is browned. Carefully turn patties over. Reduce heat to medium. Crack eggs into the centre of each patty. Cook, covered, for 5-6 minutes or until egg whites are set

Brush cut side of buns with oil. Toast cut side of buns on barbecue until golden. Remove from heat. Place cheese on base of buns to soften slightly. Top with lettuce, sauces, barbecue onions and patties. Serve sandwiched with roll tops and serve with sweet potato fries and coleslaw