Basic Red Wine Pan Sauce for Hamburgers or Steaks

• 4 tablespoons cold butter
• ¼ cup finely chopped shallots or green onions (white parts only)

Heat 2 tablespoons of the butter in a sauté pan over medium heat (preferably the same pan you used to cook the meat you are saucing), and sauté the shallots or onions until softened but not brown, about 2 minutes. Add the stock, wine, vinegar, and mustard and bring to a boil over high heat, stirring