Dissolve the salt in 4 cups water in a large container. Add the duck and bay leaf, cover and refrigerate overnight.
Preheat the oven to 400 degrees F.
Drain the brine from the duck and discard the bay leaf. Place the duck, duck fat and fresh thyme in a roasting pan. Wrap tightly with plastic wrap, and then with foil. Place in the oven for 3 hours. Remove the foil and plastic and allow to cool.
You may re-wrap and refrigerate the duck as is, or when cool enough to handle, strain the fat (reserve for your next batch, or for making pommes frites) and pick the meat and skin from the bones. We use the bones for making gravy and stock and you can fry up the skins for cracklings - maybe the best snack ever!
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.