In a blender or a food processor, blend the San Marzano tomatoes until smooth. Measure 1 cup and set aside. Reserve the remaining sauce for another recipe.
Heat the oil in a large saucepan over low heat. Add the onion, carrot, and celery. Stir from time to time for 10-15 minutes.
Add the duck pieces and the reserved skin. Cook stirring and turning them over until the duck pieces change color.
Stir in the garlic and cook for 1 minute or until the aroma rises.
Next, add the wine, the cup of blended tomatoes, half of the chicken stock, the sage, rosemary, bay leaf, salt, pepper, and sugar. Simmer, covered over low heat for 1 hour. Add the remaining chicken stock as the sauce reduces. Taste and adjust the seasoning as it cooks.
Once the sauce is done reducing, carefully remove the duck skin and bay leaves from the sauce.
Cook the pappardelle in a pot of boiling, salted water until done al dente. Drain and pour the pappardelle into the saucepan with the sauce and mix well over low heat.
Serve with grated Parmesan Reggiano.
