In a stainless steel mixing bowl, whisk the egg yolks and lemon juice together. The mixture should get thicker and increase in volume.
Heat a saucepan with 1 to 2 inches of water in it over medium heat until the water is simmering. Lower the heat to medium low. Place the bowl over top of the saucepan, making sure that the water is not touching the bottom of the bowl or else the eggs will begin to scramble. Continue whisking rapidly.
Little by little, whisk in the melted butter until the sauce has thickened and is light and fluffy.
Remove from the heat and gently whisk in the hot sauce, cayenne pepper and sea salt.