In a large stainless or glass bowl, whisk the egg yolks with 2 tbsp of cold water.
Place the container on a double boiler filled with very hot (but not boiling) water. Whisk until the mixture is thickened a bit and has a foamy texture.
Add the small cubes of butter one by one while continuing to whisk.
Season with salt and pepper, stir in the lemon juice. Whisk 10 seconds then serve immediately.