Although it begins life as relatively bland milk, yogurt's bright acidity and creamy texture transform it into a very different food. Although you can enjoy yogurt on its own or with fruit, it has a wide range of other uses that are easily overlooked. For example, you can use it as a milk substitute in cooking, baking or even as a beverage. Its rich, tangy flavor alters the end result subtly but leaves the dish essentially unchanged.
Hot Sauces and Casseroles
Yogurt's relatively high level of acidity is responsible for its refreshing tang, but it's problematic if you want to use it in hot dishes. The protein molecules in dairy products curdle if they're heated in an acidic environment, so the yogurt must be stabilized before you can use it as a milk replacement in sauces and casseroles. You can do that with either egg whites or a starch-based thickener such as cornstarch. Whisk beaten egg white or a slurry of starch and water into your yogurt, then heat it gently until it thickens. At that point you can use it in place of milk or cream, to make a tangy sauce for entrees or casseroles.
In Muffins and Quick Breads
In quick breads, yogurt provides an easy substitute for milk. Just whisk the yogurt briefly to make it more liquid, then use it as a straight one-to-one replacement. Yogurt typically makes muffins and quick breads taste more moist and richer, and its tang works especially well in chocolate or spice-flavored recipes. The extra acidity can make your baked goods look pale, so add up to 1/2 teaspoon of soda for every cup of yogurt. Soda counters the yogurt's tang and helps your baked goods brown as they should.
In Yeast Doughs
Yogurt can also be used as a milk substitute in yeast doughs, where it lends the finished breads or other baked goods a rich, sourdough-like flavor. It does require you make a few quick adjustments in your recipe, but they're not overly complex. You'll need to increase your yeast slightly, because yeast doesn't flourish as readily in an acidic environment. The yogurt will also yield a paler finished product, unless you correct for its effect. Adding a small amount of sugar provides extra browning and helps moderate the yogurt's tang. Alternatively, enrich the color of your baked goods by brushing them with beaten egg before they go into the oven.
Custards and Desserts
Yogurt already has a custard-like texture, especially if you drain the surplus whey overnight, or simply start with a rich, Greek- or Balkan-style yogurt. Still, for those occasions when you need the richer flavor and stable texture of a custard, you can use yogurt as a substitute for the milk or cream in the recipe. Whisk the sugar, eggs and other flavorings into your yogurt -- a bit of starch makes the mixture more stable, though that's optional -- and heat it gently over a low burner or double boiler until it thickens. You can cook it fully on the stovetop or pour it into individual custard cups or a pie shell and finish it in the oven.
As a Beverage
Yogurt can also replace milk as a cool, refreshing beverage. Shake or whisk the yogurt vigorously to loosen its texture, then add either fruit juice or a fruit puree and a bit of water to thin the mixture. In India's summer heat, yogurt-based drinks called lassi are especially popular. The yogurt is whisked with ice water or blended with ice cubes, to thin and chill it, and often flavored with rose water, sugar, cardamoms, pistachios or almonds. Some versions are lightly salted, rather than sweetened, for a different but equally refreshing effect.