INGREDIENTS
•
Ingredients (Note: All ingredients should be at room temperature for best results):
•
1 tbsp. extra-virgin olive oil, plus 1 tablespoon
•
1 cup chopped white onion
•
4-5 garlic cloves, minced
•
½ cup Parmesan cheese, grated
•
1 cup white cheddar cheese, shredded
•
½ cup Provolone, shredded
•
½ cup part-skim Mozzarella, shredded
•
1 cup plain breadcrumbs
•
¼ cup roughly chopped fresh flat-leaf parsley
•
1 large egg
•
1 tbsp. Dijon mustard
•
kosher salt and freshly ground black pepper, to taste
•
1½ lbs. ground beef sirloin
•
3 tbsp. tomato paste
•
1 tbsp. warm water