In a bowl, combine the kosher salt and chopped thyme and mix it well. Rub the salt and thyme mixture on both sides of the duck, layering it on thickly. Place legs in a shallow pan and refrigerate, covered, overnight.
Preheat oven to 350 degrees F.
In the same shallow pan, add the onion, garlic, star anise, canela, and duck fat over the legs. Cover the pan with aluminum foil. Roast in the oven for 3 hours.
Meanwhile, soak the cornhusks in warm water for 1 hour.
To make the dough for the tamales, moisten the instant corn flour with the warm water. Set aside. Beat the shortening in a mixer until creamy and fluffy, about 10 minutes, then fold in the corn flour and chicken stock.
After 3 hours remove the legs from the fat, remove the outer skin and shred the meat away from the bone and set aside.
To assemble the tamales, open the soaked cornhusks and add 2 tablespoons of dough. Spread the dough over the cornhusk leaving a 1/2-inch border. Put 1 tablespoon of the shredded duck meat in the center in a line. Fold the cornhusk over, enclosing the duck in the dough, and secure the tamale with a string or ripped-off piece of the cornhusks. Repeat the process until all the dough and filling is finished.
In a double boiler or steamer, steam the tamales for 20 minutes. Turn off heat and allow to sit for 10 minutes before serving.
To make the sour cherry mojo: Soak the dried cherries in a bowl with red wine for 1 hour.
In a medium saucepot, heat 1 tablespoon of oil over medium high heat. When the oil has begun to smoke, add the shallots, chipotle, and garlic. Cook for 5 minutes then deglaze with red wine vinegar and duck stock. Cook for 3 minutes then add the cherry mixture. Cook for 30 minutes until the liquid has thickened. Add the parsley. Season with salt and pepper.
To serve, remove the tamale from the steamer. Open the tamales and serve with a spoon of the cherry mojo.