Sorrel Sauce/Gravy/Pesto/Dip This is probably more of a Sorrel Sauce, which doesn't sound good. For whatever reason we don't seem to have very many words for 'sauce' in the English language. Sauce, condiment, gravy, dressing. Anyhow, we'll call this one a pesto for lack of a better name. Firstly, you may be asking yourself - what is sorrel? Sorrel is an herb! You've probably seen sorrel and just didn't know what it was. It's very hardy, drought tolerant and is a bit weedy (if