Add the egg yolks and lemon juice to a blender and blend for several seconds. With the blender running, slowly drizzle in the melted butter. Turn off the blender and add the mustard, smoked paprika, cayenne and salt. Blend again and taste. Adjust the seasoning as needed. Keep warm until ready to serve.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.