6 cups duck fat, melted (available at good butcher counters or amazon.com)
Combine parsley, thyme, oregano, shallots, and garlic in a food processor and pulse until the ingredients are finely minced. Add salt. With the machine running, drizzle in the oil in a steady stream until you have a fine, thick paste.
Rinse and clean the duck legs with water, pat dry. Trim off the large pieces of fat, reserving them for the confit.
Season the exposed, cut side of each leg (the part that has no skin) with 1 tablespoon of the herb/garlic paste.
Press the legs together where the cut sides are exposed and lay the pairs of legs in a casserole dish just large enough to fit them snugly. Cover the dish with plastic wrap and weigh the legs down with the bottom of another casserole dish filled with cans or bricks.
Let the legs cure in the refrigerator overnight.
Preheat the oven to 300°F.
Scrape the excess herb/garlic paste from the legs and transfer them to a Dutch oven or deep casserole dish. Melt the duck fat over medium low heat, until completely translucent and cover the legs with at least ½ inch of the fat.
Heat the legs and fat over medium heat until the fat comes to a slow simmer. Cover the pot with a tight-fitting lid or seal it tightly with aluminum foil.
Cook the legs in the oven for 4 hours, or until the meat is tender but not falling off the bone. Take the lid off the confit to let the steam out and then place directly in the refrigerator (on a trivet or pot holder) to cool. Refrigerated under a layer of fat, the duck confit legs will keep for up to 3 months.
To use the confit, remove the legs from the fat. Leaving the skin intact, scrape the fat from the legs with a spoon or knife. The fat can be discarded or set aside and reused for another purpose. At this point, you can either reheat the legs in a skillet over medium-high heat, searing them on both sides until the skin is browned, or pull off and discard the skin and pull the meat off the bone. The finished duck meat can be used in your favorite pasta, holiday risotto, or the following Classic Cassoulet Recipe!