Preheat grill to medium. In large bowl, combine egg, onion and bread crumbs. Add ground beef and sausage; mix well. Shape into six burgers.
Grill burgers for 10-12 minutes, turning once, until a meat thermometer reads 160 degrees.
Serve burgers on buns with pesto, provolone cheese, tomato and basil.
Serving suggestion: For spicy burgers, substitute Hot Italian Sausage.