Because parsley is so widely available and inexpensive, it is often taken for granted. Many cooks put a parsley sprig on a plate without really thinking about what it adds. A sprig, in fact, doesn’t add much except for a little clichéd color. But when parsley is chopped, finely and at the last minute, and added to seafood and meat sauces, it contributes an ineffable complexity and nuance. Indeed, it is often the missing element in a long-cooked sauce that has lost some of its vitality and freshness for having spent so many hours on the stove.