Sweet and mild rice wine vinegar, or "rice wine vinegar" as it's often abbreviated, lends a tart flavor to many Asian dishes. Produced like sake from fermented rice, rice wine vinegar has no equivalent Western-made ingredient. Still, if you're making a recipe that calls for it, a number of other types of vinegar make satisfactory substitutes. Although the resulting flavor will be slightly off, a few minor tweaks will help you achieve the desired taste.
White Wine Vinegar
Western-style white wine vinegar is pale in color, similar to rice wine vinegar, but is stronger, more acidic and has less nuances than rice vinegar. To make the substitution it's best to use a decent-quality, well-aged, white vinegar because it's more mellow. Use slightly less white vinegar than the recipe calls for; or dilute it with water. Rice vinegar is sweet, so add a pinch of sugar, a few drops of honey, a teaspoon of agave syrup, or any other sweetener you prefer.
Other Wine Vinegar
Other wine-derived vinegar, like champagne vinegar, sherry vinegar or white balsamic vinegar, also makes a suitable substitute for rice vinegar. Champagne vinegar and sherry vinegar, like white, vary in quality. Young, rough versions will need to be diluted, so older, subtler brands are preferable. White balsamic vinegar is something of a marketing gimmick, as it lacks the softness of true balsamic. However, it is a passable option. Note: all of these substitutes should be sweetened with the aforementioned flavorings, though white balsamic--which has some sweetness of its own--requires less.
Apple Cider Vinegar
Although apples and rice couldn't be more unlike as ingredients, apple cider vinegar has an aroma similar to rice wine vinegar. As with wine vinegar, apple cider vinegar is typically stronger and sharper tasting than rice vinegar, so it must be lightly sweetened and diluted to serve as a fitting replacement.
Wine Over Water
For a flavor that resembles rice vinegar more closely, consider using a splash of rice wine -- rather than water -- for dilution. Either a Chinese-style rice wine, such as Shaoxing wine, or a Japanese-style sake is appropriate. Mirin, a sweetened Japanese rice wine, is an even better option because of its sugar content.
The Red and The Black
A recipe calling for rice wine vinegar typically means the white variety, but there are two others you may encounter as well. One is a red rice vinegar, used in sauces or as a dip. Substitute a plain red wine vinegar or malt vinegar; lightly sweetened and salted to replicate the original. Black rice vinegar is a common dipping sauce for dumplings, marked by it's bold flavor. If your pantry is well-stocked, use a mixture of 3 to 4 parts sherry vinegar and 1 part balsamic vinegar to replicate the taste of black rice vinegar.