Not unlike yogurt or sour cream, crème fraîche is made by inoculating cream with bacteria that causes fermentation. Its taste is similar to sour cream, but slightly less acidic. It is more versatile than sour cream because, unlike sour cream or yogurt, it can be boiled without curdling. It is available commercially, however sometimes it is difficult to find. If you are using it in a cold dish you can usually substitute sour cream. It is also quite easy to make your self, you will find directions in our recipe for Mille Feuille with Double Salmon and Crème Fraîche.