Vinegar is commonly used in many different food items, including salads, soups, stir-fries, sauces and marinades. While most prepared foods will not have be overly flavoured with vinegar, it's fairly easy to make a mistake when cooking yourself, especially if you are dealing with a recipe you are not familiar with, and too much vinegar can ruin an otherwise well-prepared dish. However, there are some ways to reduce the vinegar taste in food after the fact in many cases.
Allow cooked food to continue cooking over the lowest possible temperature, stirring regularly with a wooden spoon. As the food cooks, the acids in the vinegar that give it its strong taste will be reduced. Taste the food every few minutes until the vinegar is reduced to your liking, adding water or broth to keep food moist if necessary.
Add a small amount of table sugar to the recipe, stirring and tasting the food each you add sugar. For small recipes less than 2 cups, add just 1/4 tsp at a time. You don't want to add too much sugar to a recipe that doesn't call for it.
Double the recipe without adding the vinegar the second time. Depending on the cooking stage, you may have to prepare the halves of the finished product separately and combine them at a larger stage. For items like a salad where too much vinegar is used for dressing, you can simply add more of the salad ingredients and retoss the salad.
Use coarsely ground black pepper to season the food instead of regular black pepper. The larger grains of black pepper have a more intense, noticeable flavour, which can help mask the acidity in the vinegar.
Soak foods that have been pickled in water for 24 hours in an airtight container, changing the water after eight hours. If you need to reduce acidity quickly, rinsing food under cold running water can help, but soaking is the best method.
Let food items like salads dressed with vinegar where the vinegar was not absorbed into the food to drain in a colander in the sink for 60 minutes, tossing the food regularly. If necessary, the food can be blotted with paper towels before being remixed.