Here are the following ingredients:
Here are the following shopping items to buy:
Follow these cooking methods/directions:
Grill patties on a lightly oiled grill over medium-high heat in a closed barbecue for 10 to 14 minutes for ¾-inch (2 cm) thick patties, turning twice or more, or until digital instant-read thermometer inserted sideways into centre of each patty reads 160°F (71°C).
Meanwhile, combine mayonnaise, capers and dillweed (if using) in a small bowl. Toast ciabatta buns.
Place patties on toasted buns, spread with mayo mixture then top with spinach, prosciutto and onion and sprinkle with feta cheese.