In a saucepan over medium heat, combine the tomato paste, beef stock and garlic. Saute for about a minute, then add in the tomato sauce, vinegar, brown sugar, oregano and red pepper.
Bring the mixture to a gentle boil then reduce the heat. Cook, stirring occasionally, until thickened, about 20 minutes. Stir in the basil.
make the burgers:
Place the bread in a bowl and add enough milk to soak the bread. Allow the bread to sit for a few minutes, then squeeze all excess milk out of the bread.
Place the bread in a large bowl and add the ground beef and ground pork. Season with salt and pepper. Add in the parsley, garlic, onion and Parmesan and gently mix, making sure to not overwork the meat.
Form the mixture into 4 large patties.
Heat a grill pan or an outdoor grill over medium high heat. Drizzle olive oil over the patties and then cook, turning once, until cooked, about 10 minutes.
In a small saucepan, melt the butter. Add the garlic and allow to cook for 30 seconds to 1 minute. Remove from the heat.
Brush the outsides of each slice of bread with the garlic butter. Build four burgers, with the buttered sides facing out. Layer each with some of the balsamic marinara ketchup, a slice of mozzarella, a patty, a slice of provolone, and more ketchup. Place the burgers on the griddle and cook until the bread is toasted and the cheese is melted.
Notes
source: Every Day with Rachael Ray July/August 2013Nutrition information provided as an estimate only. Various brands and products can change the counts. Any nutritional information should be used as a general guide.