Whatever the reason that you can't use wine -- unavailability, religious, ethical, vegan diet -- you can find several substitutes for wine in a recipe. Use another ingredient to match the function that the wine would have performed.
What Does Wine Do?
The addition of wine during cooking is not just to introduce fresh, fruity aromas. For a start, the acid in wine is an effective marinating tool that can tenderize not only poultry but also sinewy steaks such as flank. In the same manner, wine's acidity helps cut through sauces that are heavy in fat, an essential function in thick, heavy stews such as boeuf Bourguignon. Wine is vital in deglazing a pan in which chops or steaks, for example, have been seared, breaking loose the herb and fat crust as the first step in building a sauce. Because of its alcohol content, wine also provides the right environment for poaching fruit such as pears and apples, along with sugar and spices. Where caramelization is important, however, fortified wines or spirits perform the task better.
Red Wine Alternatives
Without a robust Burgundy wine, boeuf Bourguignon becomes a generic beef stew, and without wine, coq au vin also sacrifices much of its distinctive character. Nevertheless, versions of these dishes can still be enjoyed if you wish to eliminate wine. Both balsamic and red wine vinegar come from grapes that have been allowed to ferment to the point where the acidity takes over and the flavor is soured. Small doses of either will deglaze a pan, and the more exclusive brands contribute their own set of complex aromas. To evoke red wine's fruity notes, cranberry, pomegranate or red grape juice can all perform when added to a beef or chicken stock. It is important, though, to source natural juice rather than fruit drinks, which have little depth but overwhelming amounts of sugar.
Replacing White Wines
If you're making risotto or bouillabaisse, you need not despair if you don't have white wine on hand. In risotto, the wine reduces so much during the early stages of cooking that it is present in little more than aroma only, so extra vegetable or chicken stock can stand in. For fish-based or shellfish dishes that are traditionally steamed in white wine, clam juice has the requisite sourness that a white wine brings. Otherwise, white grape juice, natural apple juice, lemon juice and white wine vinegar can all substitute for white wine. Arguably the closest match comes in the form of verjus, the sometimes difficult-to-source juice of unripe grapes, which is subtler than vinegar but with a tart, fresh taste. Use it in marinades, dressings and sauces.
Sparkling and Sweet Wines
Even Champagne has its own vinegar counterpart, not surprisingly called Champagne vinegar, which can stand in for wine in shellfish or poultry dishes that normally use a dash of bubbly. Otherwise, a splash of ginger ale and some soda water added to a stock will recreate the sparkle and sweetness. While most white wine dishes call for a dry, crisp wine, some desserts match better with a sweet dessert wine such as a Riesling or Gewurztraminer. A white grape juice mixed with lemon juice won't trump the Alsace wine's spice and fruit aromas, but it will provide balance and acidity for fish stews or spicy Asian shrimp stir-fries, for example.