One 3-inch piece ginger, peeled and cut into coins
6cups rendered duck fat or olive oil, or a combination
Mesclun salad, for serving (optional)
Instructions
Grind the star anise, coriander seeds, and peppercorns with a mortar and pestle or in a spice grinder (or put them in a plastic bag and bash them with a rolling pin). Use a vegetable peeler to remove the zest from the orange in long strips and scrape off any white pith from the underside with a paring knife. Mix the spices, zest, and salt in a bowl. Put the duck in a large bowl and rub all over with the salt mixture. Press the ginger and orange zest into the legs, cover, and refrigerate for 24 to 48 hours.
Heat the oven to 300°F. Remove the duck from the salt mixture and rinse off the salt; blot dry. Warm the duck fat in a saucepan over low heat just until it’s pourable. Put the duck and ginger in a baking dish or roasting pan in one snug layer. Pour enough of the duck fat over the legs to just submerge them. (You may not need all of it; and if you don’t have enough, add olive oil.) Transfer to the oven and cook, undisturbed, until you can easily insert a fork into the thickest part of the meat in a few of the legs and the fat becomes viscous, 3 to 4 hours.
Remove the legs from the fat but don’t scrape off the excess. Discard the ginger and orange zest. When they’re cool enough to handle, tightly wrap the legs individually or in pairs and refrigerate. Pour the fat into a separate storage container. (The legs will keep for up to 2 weeks; the fat will keep, refrigerated, for months. Freezing the legs and fat will extend the storage time to a year.)
To serve, heat a couple tablespoons of the fat in a skillet over medium-low heat. Add 1 or more legs at a time and cook, turning as necessary, until brown and crisp, 10 to 15 minutes. Serve with a mesclun salad, if desired.