If clarifying your own butter, make sure it's cooled to lukewarm.
If using already clarified butter, warm it to liquefy.
Place egg yolks and wine in a double boiler (or in a heat-proof bowl set over a pan of simmering water).
Whisk vigorously until the mixture is very pale and the whisk leaves a trail, 3 to 4 minutes.
Remove from heat; continue whisking until mixture is the same temperature as the butter, about 30 seconds.
Whisking constantly, add butter to the egg mixture a drop at a time at first and gradually increasing to a steady stream.
When fully incorporated, stir in the water and lemon juice, and season to taste with salt and cayenne pepper.
Serve immediately, or keep warm over a pan of simmering water removed from heat.