Sautéed Swiss Chard with Hazelnuts and Garlic

INGREDIENTS

• 1/2 cup chopped hazelnuts
• 2 tablespoons butter
• 1 anchovy fillet
• 2 garlic cloves, sliced
• 2 pounds red Swiss chard, leaves torn and stems trimmed into 1-inch pieces
• 1 to 2 teaspoons sherry vinegar
• Kosher salt and freshly ground black pepper