1Soak the cherries in the vinegar for at least an hour.
Put 3 1/4 cups of the stock in a heavy-bottomed saucepan and bring to a boil over medium-high heat until reduced to 1 cup. This will take 15 to 20 minutes.
2Meanwhile, oil a roasting pan, brush the duck breasts with soy sauce and honey, sprinkle with salt and pepper and sprinkle lemon peel over duck. Roast in a preheated 450 degree F. oven for about 15 to 20 minutes for medium, less if rarer meat is desired.
Caramelize the sugar in a small heavy-bottomed saucepan or skillet by heating it over medium heat without stirring until it is syrupy and very dark brown. Dissolve it in the remaining 1/4 cup duck stock.
3When the duck breasts are done, place on a warm plate, cover with foil and set aside in a warm place. Deglaze the roasting pan with the caramel and stock mixture and add that to the reduced stock, stirring well with a wooden spoon until the sauce is thick and almost syrupy. Drain the cherries and add them to the sauce.
4Place half a duck breast on each plate. Top with several tablespoons of sauce and sprinkle with nuts and parsley sprigs.