A rich traditional French sauce with an acid note, which goes well with white-fleshed fish.
Step 1. In a stainless steel bowl, whisk the egg yolks and lemon juice together until the mixture is thickened and doubles in volume.
Step 2. Place the bowl over a saucepan of simmering water (bain-marie). The bowl should float on the water and not touch the bottom of the saucepan.
Step 3. Continue whisking the mixture and do not let the eggs get too hot and scramble. Drizzle in the melted butter slowly while whisking until the sauce is thickened again.
Step 4. Remove from the heat and add pepper and salt.
Step 5. Cover and keep it warm until serving.
Tips: Sauce should be made just before the meal time so it will not be cold.