You could substitute rice vinegar for cooking sherry. Rice vinegar has a mild, sweet flavor.
A cooking sherry substitute can be a few choices. A brandy, cognac, or a port wine is an ideal substitute.
No, there's no need to keep cooking sherry in the refrigerator. It's fine to store it at room temperature.
No. Sherry wine is a drinkable sherry, that can be used in cooking, while sherry vinegar is used only for cooking.
Your best bet is to go to the wine and/or liquor store and get real sherry (wine fortified with brandy). Avoid the grocery store stuff labelled "cooking sherry".
Sherry is a wine that is fortified with brandy. Medium dry sherry is a cooking wine that is used in a variety of recipes.
No, they are not the same product and will not produce similar results.
Well, its cheap sherry that you would consider not quite good enough for drinking, or any sherry that has been open to the air for long enough to alter its flavour slightly (say a few weeks) but you don't want to just throw it away.
18-20% alcohol
When cooking with something like sherry, you need not worry about a recovering alcoholic eating food that has sherry in it. Cooking removes any significant alcohol in the food dish, and for all intents and purposes, only adds a good flavor. I would not worry about substituting another ingredient for the sherry. Use the sherry.
Pale dry Sherry is light while red Sherry is more robust in composition. I prefer the red Sherry for cooking or giving to my guests for a nip or two.
By its vinegary taste and smell.
Yes, any good quality white wine can be used instead of sherry.
Dry sherries (Madeira, Sack, etc.) are very commonly used in cooking. I have never heard of cream sherry being used in cooking, though it would make sense for some types of dessert recipes.