Serious Eats: Recipes
Herb sauces are great stuff: they let the flavor of an herb come through proud and clear while lightly cloaking food. But they are prone to breaking—let an herb purée sit for five minutes and the solids will clump together and leave an ugly pool of green water on the plate. A small pinch of xanthan gum will hold the sauce together and provide a velvety texture to what may otherwise be too thin.
Xanthan gum is one of the most common and easy to use modernist ingredients. You can use it to thicken just about any liquid, and a little goes a long way. (Conversely, too much will turn your sauce into spackle.) It is relatively easy to find as these ingredients go, especially as it's also used in gluten-free baking, but you can also buy it at L'Epicerie.
Use this coulis as a light sauce on roasted potatoes, pan-seared chicken breasts, or as a salsa on tacos.