Verjuice от John Spottiswood

A medieval ingredient that's making a comeback, verjus is a sour juice made from unripened red or white grapes. Vinegars in salad dressings sometimes create off-tastes in the wines that accompany a meal. Verjus doesn't, so it's a good substitute for vinegar if you're planning to serve an expensive wine with dinner. Some people also mix it with sparkling water and ice to make a sophisticated non-alcoholic drink. After the bottle is opened, store verjus in the refrigerator, where it will keep for about a month. If you can't use it that fast, pour it into ice cube trays, freeze, then store the cubes in a plastic bag in the freezer. Though becoming more popular, verjus is still hard to find. Look for it in gourmet specialty shops.