In Japan, hot springs (onsen) have always been used to prepare soft-boiled eggs. With a sous vide appliance, you can achieve a constant water temperature like in the Japanese onsen. For the preparation of onsen eggs, the temperature should not exceed 63.7° C. This makes it perfectly semi-liquid and soft without the egg white completely solidifying. Of course, only very fresh eggs are suitable for this preparation. There is a simple test to ensure this. Place the eggs in a container of cold water. 1. if the egg sinks and falls on its side, it is fresh. 2. if it stays at the bottom but stands up, it is a little older and should be eaten soon. 3. if it floats to the top: throw it away!

The eggs should be left in a warm water bath for between 45 minutes and 1 ½ hours, depending on the desired consistency.