Mix all the patty ingredients together lightly with a small fork, do not over mix or the patty will be tough. Leave to rest for 10 minutes. Shape into 4 patties.
Brush the patties lightly on both sides with oil and cook them on a very hot cast iron griddle pan until nicely browned and cooked through. Use a large flat spatula to turn the patties.
Slice the buns in half and toast the cut sides.
To assemble, place lettuce on the bottom half of each bun, top with the meat patty, cheese slices, add the sliced avocado, a slice of tomato, and add the onion and garnish with micro herbs.
