What could I substitute for Sherry in a soup recipe?

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Dear Dr. Vinny,
What could I substitute for Sherry in a soup recipe?
—Adria, Conway, Mass.
Dear Adria,
I love Sherry. Like Port or Vermouth, Sherry is a fortified wine, which means a small amount of distilled spirits are added, boosting the alcohol by volume to the 15 to 22 percent range. It’s made in a variety of styles, from clear and pale to sweet and rich, but many show off wonderful complex nutty, spice, orange peel or caramel notes. The non-sweet versions are typically what are used in recipes, so you’ll see them referred to as “dry Sherry” (“dry” meaning the opposite of “sweet”).
One of the uses of Sherry in a recipe is to deglaze a pan. Any form of alcohol will accomplish more than water as a deglazing agent, because the proteins that can stick to the bottom of the pan are more soluble in alcohol, so deglazing the pan releases more of those flavors into your dish. Sherry also has a wonderful nutty, spicy note.
But you might not have a bottle of Sherry lying around when you’re about to make some lobster bisque. You can use a white wine, brandy or dry vermouth (or, depending on the recipe, red wine, Port, Madeira or Marsala, knowing they will leave some residual flavor). You can also try vinegars—apple cider, wine vinegar or even rice wine vinegar.
I’d recommend buying an affordable bottle of Sherry, because once you start cooking with it, you might understand why so many recipes call for it. Even better, because Sherry is fortified, it lasts far longer than an open bottle of table wine.
—Dr. Vinny