 In appearance, it is light yellow and opaque, smooth and creamy.Béarnaise is a traditional sauce for steak.The sauce was accidentally invented by the chef Jean-Louis Françoise-Collinet, the accidental inventor of puffed potatoes ("pommes de terre soufflées"), and served at the 1836 opening of "Le Pavillon Henri IV", a restaurant at Saint-Germain-en-Laye, not far from Paris.