Place the butter in a saucepan and clarify to separate the butter and the fat; keep at room temperature

Reduction

In another saucepan, add the water, vinegar, onion, and peppercorns, reduce by half, strain the liquid, and keep it at room temperature.

In a double boiler, over low heat, add the egg yolks. Add half the liquid and mix, whisking together until light and fluffy. Slowly add the butter to the eggs, whisking in a clockwise motion. Ensure the water is not too hot in the double boiler, or it will cook the eggs too fast. If the sauce looks like it is getting too thick, add some more of the reduction. Add all the butter; the eggs will hold without breaking the sauce

Season the sauce with salt, pepper, lemon juice and Worcestershire sauce to taste. Remove from the heat and place in a plastic bowl; keep at room temperature