Moist Estonian Hamburgers - Sutter Home Family Vineyards

Ingredients

• 2 lbs. 85% lean ground beef
• 4 slices white (American) bread, crusts removed, torn into pieces
• 2 eggs
• 1 large onion, finely chopped
• 2 teaspoons salt
• 1 teaspoon black pepper
• 4 heaping Tablespoons sour cream
• flour