Prepare all of the ingredients. Preheat the oven to 400 deg. Preheat the grill to 375deg
Combine mayo and balsamic vinegar and leave in fridge until ready to build the burgers
In a large bowl, combine all of the ingredients for the burgers and form into 4 inch patties. Once grill is ready, cook on each side for 7-9 minutes. Remove from grill, layer with slice of mozzarella cheese and let rest for 5 minutes.
While the burgers are cooking, lay the ciabatta buns on a baking sheet face up. Combine melted butter, parsley and garlic powder, and brush each bun. Put in oven for 5-7 minutes until just golden.
Build your burgers - put a layer of balsamic mayo on the bottom bun, then 4 slices of salami, a burger patty (with mozzarella cheese), onion and top bun that was spread with more balsamic mayo.
Notes
If you like Kalamata olives, you could slice them and put in the burger or leave them whole and top the burger off with a toothpick and an olive or two.