Spinach and Sun-Dried Tomato Mozzarella Stuffed Burger - Sutter Home Family Vineyards

Ingredients

• 2 pounds ground sirloin
• 2 tablespoons worcestershire sauce
• 2 teaspoons kosher salt
• 1 teaspoon fresh ground black pepper
• 1/2 cup sun ripened sun dried tomatoes in olive oil, diced
• 1 cup fresh grated parmesan cheese
• 1 cup fried onions
• 1 cup frozen spinach, defrosted and drained well
• 1 medium egg
• 2 shallots, diced and sauteed
• 2 tablespoons minced garlic, sauteed
• 1/4 cup balsalmic vinegar
• 1 tablespoon salted butter
• 3 ounces spinach florentine sauce
• 6 fresh mozzarella slices
• 6 bun sized onion rolls