Preheat the oven to 200ºF.
Season the duck meat with salt and pepper and place in a large, shallow baking dish. Arrange the garlic evenly over the meat and tuck in the bouquets garnis. Add the oil and the reserved duck fat, cover with a sheet of aluminum foil, and bake until the meat pulls away form the bone, 12 to 14 hours.
Remove from the oven and cool completely. Strain and reserve the fat. Pick the meat from the bones. The meat can be used as is or it can be placed in a stoneware container, covered with some of the strained fat, making a 1/4-inch layer over the meat, and stored in the refrigerator for up to 1 month.
Store the oil in an airtight container in the refrigerator for up to 1 month and use like butter.
Yield: about 2 cups