Don't throw away herb stems. Instead, add them to stews, broths, and soups for more flavor. Stems from herbs like parsley and cilantro can actually be used in many different ways. Add them to slow-simmering stews and soups while cooking to infuse more flavor. (Just make sure to take them out before serving.) You can also use them to infuse oils and vinegars or purée them and add them to butter.