Melt the butter over low heat and keep it warm (about 50–60 °C). Put 2 tbsp of water, 1 tbsp of vinegar, the crushed pepper and a pinch of salt into a small heavy-based saucepan and reduce by two thirds until about 1 tbsp of liquid remains.

Ingredients

• 200 gButter, without salt
• 34 gEgg, yolk, raw, fresh
• 2 15 ml tablespoonBeverages, water, tap, drinking
• 1 15 ml tablespoonWhite wine vinegar
• 0.3 gSpices, pepper, black not counted – removed
• 3 gSalt, table
• 1 5 ml teaspoonBeverages, water, tap, drinking
• 1.5 15 ml tablespoonBeverages, water, tap, drinking
• 0.5 5 ml teaspoonLemon juice, raw

Method

1. Melt the butter over low heat and keep it warm (about 50–60 °C). Put 2 tbsp of water, 1 tbsp of vinegar, the crushed pepper and a pinch of salt into a small heavy-based saucepan and reduce by two thirds until about 1 tbsp of liquid remains.
2. Set the saucepan in a hot water bath kept well below simmering, add 1 tsp of cold water and the yolks, whisk them briefly and start mounting with the butter straight away; do not let the yolks get hotter than about 65 °C.
3. Whisking briskly all the time, pour in the warm butter, drop by drop at first and then in a thin stream. While mounting, add a total of 1½ tbsp of water a little at a time; it makes the sauce lighter.
4. Adjust the salt, season with ½ tsp of lemon juice and pass the sauce through a fine sieve or cloth (it catches the pepper). Keep it only lukewarm in the water bath and serve as soon as possible; overheating makes it split and it cannot be reheated.