Lemon confit, or preserved lemon, is a popular ingredient in Moroccan cuisines and is great when you are looking to add a little brightness to a dish. It is traditionally made by packing lemons in salt for several months, but using a sous vide machine speeds up the process to about an hour. The base flavors aren't quite as complex as the traditional method but it's a great substitute when you don't want to wait a few months for preserved lemons.
When you want to use the lemon, cut away the pulp and the pith and discard. Rinse the remaining lemon peel under water to remove the excess salt then cut it into pieces.
Preheat a water bath to 183°F (83.9°C).
Place the lemon quarters, salt, and sugar in a sous vide bag and massage the salt into the lemons, ensuring that all the lemons are covered. Seal the bag and then cook for 60 minutes. Remove the bag from the water bath and empty all the contents into a glass jar.
The lemons will last in the refrigerator for several months.