Béarnaise sauce

[2][3] According to a common explanation, the sauce was accidentally invented by the chef Jean-Louis-François Collinet, the accidental inventor of puffed potatoes (pommes de terre soufflées),[4] and served at the 1836 opening of Le Pavillon Henri IV, a restaurant at Saint-Germain-en-Laye.

The restaurant was in the former residence of Henry IV of France, a gourmet himself, who was from Béarn.

[4][5] Although the sauce is a French invention, it caught on in the Nordic countries in the late 20th century, where it forms a major part of local steak cuisine with steaks and fries,[6] and is occasionally used there as topping on pizza, whether as part of the pizza or as a cold dressing put on afterwards.

The most common method of preparation uses a bain-marie, whisking to a temperature of 66 °C (150 °F),[7] where a reduction of vinegar is used to acidify the yolks.

[8] Alternatively, the flavorings may be added to a finished hollandaise (without lemon juice).