Combine the lemon juice and egg yolks in a medium stainless-steel bowl and set over a pot of simmering water. Whisk the yolks until pale yellow and fluffy. Slowly add the melted butter, a few tablespoons at a time, and whisk until thickened. Season the sauce with 2 teaspoons of the spice mixture and the salt and 1/4 teaspoon black pepper. Keep warm until ready to use. Keep the remaining spice mixture in an airtight container and keep in a cool, dark place.