In a medium bowl, combine the bread crumbs and milk. Let soak for 15 minutes.

Heat the olive oil in a medium fry pan. Add the diced onions and cook over medium heat for 6-7 minutes, or until onions begin to turn slightly soft.

Preheat grill to medium-high heat.

Transfer onions and soaked bread crumbs into a large bowl and add all of the remaining burger ingredients (beef, pork, egg, parsley, garlic, salt, pepper, oregano, red pepper and Parmesan cheese). Mix until well combined. (Tip: Take care not to overmix or the burgers may be tough.)

Shape mixture into 6 patties

Grill burgers over medium-high heat until cooked (Internal temperature reaches 160°F).

Place the hamburger buns on the grill for 1-2 minutes. (optional)

Assemble the burgers with Provolone cheese and marinara sauce.