Preheat the oven to 90°C/200°F.
Carefully remove the yolks from the salt. By this stage, the yolks should be somewhat firm and sticky.
Rinse the yolks gently with cold water, and place them on some kitchen paper to dry. At this stage, the yolks will look a bit like shiny dried apricots.
Generously oil a wire rack and place it on a baking tray lined with baking paper.
Place the yolks onto the wire racks.
Bake for about 90 minutes, or until the yolks have dried and are firm to the touch.
Let the yolks cool completely.
The cured yolks can be kept in an air-tight container in the fridge for up to 3 months. It is important that there is no moisture in the container, so I would also recommend lining the container with a paper towel to absorb any possible condensation or moisture.