Let’s start with the sun-dried tomato pesto. Place together the sun-dried tomatoes, basil, parsley, garlic, and pine nuts in a food processor or blender and process until well blended. Throw in the vinegar, tomato paste, and crushed tomatoes, and process. Stir in the olive oil and Parmesan cheese, and season with salt and pepper to taste. Set aside.
Let’s roast the tomatoes. Preheat your oven to 400F. Slice the tomatoes into thick slices {1/3-1/2 inch} and place on an ungreased cookie sheet. Drizzle with olive oil and season with Italian seasoning and salt and pepper to taste. Cook at 400F for 10 minutes, or until tomatoes have started to crinkle.
Combine the ground beef and ground Italian sausage in a large bowl. Add the balsamic vinaigrette and season well with Italian seasoning and salt and pepper to taste. Divide into 4 large patties.
Heat your grill or a table top grill to medium-high heat. Cook the patties for 5 minutes each side or until juices run clear. Top the patties with a large slice of mozzarella each and cook an additional 2-3 minutes, or until the mozzarella melts slightly.
Mix together the 4 tablespoons of mayonnaise and 4 tablespoons of sun-dried tomato pesto in a small bowl or ramekin to make the aioli and set aside. Toast the buns if desired.
Assemble the burgers by spreading the sun-dried tomato pesto aioli on the buns and then layering each with a burger with melted mozzarella, a chunk of roasted tomato, a couple of basil leaves, and the top bun. Serve and enjoy!