• 1 tablespoon balsamic vinegar
• 1 tablespoon extra virgin olive oil
• salt and pepper to taste
• 4 thick slices tomato
• 1 ⅓ pounds lean ground beef
• 1 tablespoon tomato paste
• ¼ cup chopped fresh basil
• ¼ cup grated Parmesan cheese
• 1 clove garlic, minced
• ¼ teaspoon black pepper
• 4 ounces fresh mozzarella cheese, sliced
• 4 hamburger buns, split

Directions

1. Whisk balsamic vinegar, oil, salt, and pepper in a small bowl. Pour over tomato slices to marinate.
2. Preheat an outdoor grill for medium-high heat and lightly oil the grate.
3. Mix ground beef, tomato paste, basil, Parmesan cheese, garlic, and 1/4 teaspoon pepper in a large bowl. Form beef mixture into 4 equal patties.
4. Cook on the preheated grill until the burgers are cooked to your desired degree of doneness, about 5 minutes per side for well done. An instant-read thermometer inserted into the center should read 160 degrees F (70 degrees C). Top each burger with mozzarella cheese; allow to melt. Serve on hamburger buns with marinated tomato slices.