Good yogurt (you can make your own; see page 552) is sour and rich and practically a sauce on its own; add a little salt and you’re set. The group of recipes here builds on that, taking yogurt and adding various seasonings or chopped vegetables to it, in the traditions of (mostly) the Middle East and India, where yogurt sauces are called raitas.
There is so much good yogurt around these days — including goat and sheep yogurt — that you can easily avoid inferior varieties, including those that contain gelatin or pectin and those that don’t contain live cultures. The best yogurt may be thick or thin; it may have a hard, almost cream cheese–like layer on top, or it may not. But what it does have is a fresh, sweet-sour smell and delicious flavor.