In a medium bowl, whisk together the kosher salt and sugar until fully combined.

Spread half the mixture evenly in an 8x8” glass baking dish or tupperware.

Use the back of a spoon to create 4 small indentations, evenly spaced.

Carefully place one egg yolk into each indentation.

Gently cover the yolks with the remaining salt mixture, then cover the container tightly with a lid or plastic wrap.

Refrigerate for 4 full days.

After curing, preheat oven to 150°F. Gently brush the salt mixture off each yolk, then rinse in a bowl of room temperature water to remove excess salt.

Pat each yolk gently dry with paper towels.

Lightly coat a wire cooling rack (set over a baking sheet) with nonstick spray. Place yolks on the rack.

Bake at 150°F for 1½ to 2 hours, until firm and dry to the touch. Let cool completely.

Note: If your oven doesn’t go that low, place yolks in an unheated oven for 2 days to air dry.

Once cooled, store yolks in an airtight container in the fridge. They’ll keep for up to 1 month.