2 egg yolks
1/4 lemon, juiced, or to taste
1 pinch of sea salt
1 pinch of cayenne pepper
1/4 cup salted butter melted and heated
Beat egg yolks, lemon juice, salt and cayenne pepper together in a bowl, or blender, until smooth.
Slowly stream the heated, melted butter into the egg yolk mixture, while whisking, to incorporate.