Onion Slider Burgers - Sutter Home Family Vineyards

Ingredients

• 3 large yellow onions
• 1 TBSP butter
• 1 TBSP olive oil
• ½ cup mayonnaise
• 1 clove garlic crushed
• ¼ tsp. minced flat leaf parsley
• ¼ tsp. Dijon mustard
• 1 ½ pounds chilled ground beef (80/20 lean to fat ratio)
• ¾ tsp. ground black pepper
• ¾ tsp. salt
• 1 dozen kings Hawaiian dinner rolls