Using sherry vinegar substitutes is necessary when this somewhat unusual ingredient isn’t on hand in the kitchen.
Sherry vinegar is a wine vinegar from Spain that is made from sherry. It is aged for at least six months. Like most wine vinegar, it is a little sweet, and the dryness varies depending on the brand and the wine grapes used in production. Flavors can range from nutty or caramel to molasses. Also, if you are avoiding alcohol, you may want to skip using sherry vinegar as different kinds of wine vinegar do still contain some level of alcohol. 
Sherry Vinegar Substitutes
Sherry vinegar substitutes are essential because the original ingredient is highly valued for its depth and complexity of flavors. For that exact reason, no substitution will be perfect, but sherry vinegar can be hard to find in your standard grocery store. Fortunately, there are a few substitutions that will work in a pinch, they include sherry, rice wine vinegar, champagne vinegar, apple cider vinegar, and red wine vinegar among others. Let us take a look at them below.
Rice Wine Vinegar
This is also sold under the term rice vinegar in grocery stores, and can typically be found in the International or Asian specialty section. It is close in sweetness and acidity to sherry vinegar, although it is quite a bit thinner in taste. However, if you have this available, it is an excellent substitution that will not noticeably shift the taste of a dish. 
Champagne vinegar is much sweeter than sherry vinegar, so it should be used cautiously. Champagne vinegar is good for vinaigrettes, pasta salads, and light sauces. You can also cut the sweetness by blending it with white wine vinegar, which is much harsher.
Apple Cider Vinegar
Apple cider vinegar provides a bit more of the complexity one expects from sherry vinegar, but it is much lighter and sweeter, with less nuttiness. It is also very mild, so it’s great for salad dressings or other raw dishes. Additionally, apple cider vinegar has lots of health benefits, from preventing heartburn as well as helping with eczema. Therefore, it’s never a bad idea to work a little more of it into your diet.
Red Wine Vinegar
Red wine vinegar is the strongest and most acidic of the vinegar listed here, but it also has a great, bold taste. Red wine vinegar is a good substitute when the recipe is something hearty, like meat or roasted vegetables. It can also be used in dressings, but it will taste noticeably different than sherry vinegar, so if possible, cut it with something mild like apple cider or rice vinegar. 
If you have a bottle of actual sherry lying around, you can use this as an effective substitution. Keep in mind the type of sherry it is, as flavors can vary widely. If possible, try to stick with dry sherries, and substitute at a 1:1 ratio.