A dry white wine, such as a Sauvignon Blanc or Pinot Grigio, is the best choice for French Onion Soup. The acidity of the wine helps to balance out the sweetness from the onions and compliments the savory flavors in the soup. In addition, white wine won't overwhelm or change the flavor of your soup like red wines can. If you prefer to use a red wine, then go with a light-bodied variety like Pinot Noir. We used cooking sherry as that's a common ingredient in an American French Onion soup.