Combine onion, parsley, mince, soup mix in a bowl. Mix well. shape into 4 patties.
Cook patties under preheated grill or hot plate for 10 minutes or until cooked, turning halfway through cooking.
Spread lower half of buns with tomato sauce. Top with patties, lettuce, tomato, beetroot and onion. Spread remaining bun half with mayonnaise and place on top of salad to complete burger.