Americans usually serve roast duck with a sweet sauce, but this savory French sauce with olives is worth investigating.
Prepare:
      Crispy Roasted Duck
Rinse and pat dry:
      2 pounds chicken wings, chicken backs, or chicken drumsticks
Heat in a heavy Dutch oven over medium-high heat until shimmery:
      2 tablespoons vegetable oil
Add the chicken and brown on all sides until the color of dark toast. Remove the chicken to a plate and add to the oil:
      2 cups chopped onions
Cook, stirring, over medium-high heat until browned and crisp around the edges, 12 to 15 minutes. Sprinkle over the onions:
      2 tablespoons all-purpose flour
Cook, stirring, for 1 minute more. Return the chicken to the pan and add:
      6 cups chicken stock
      2 cups dry white wine
      1/3 cup tomato paste
      1 bay leaf
      12 large sprigs fresh parsley
      1/4 teaspoon dried thyme
      1/4 teaspoon fennel seeds
      1/4 teaspoon ground black pepper
Simmer gently, uncovered, for 2 hours, periodically skimming off the fat with a spoon. Strain the sauce through a sieve, discarding the solids, then return it to the pan and boil over high heat until thickened to a saucelike consistency. Bring to a boil in a medium saucepan over high heat:
      4 cups water
Add:
      1 cup pitted brine-cured green olives
Boil the olives for 2 minutes, then drain. Taste. If the olives seem very salty, repeat. Add the olives to the sauce and simmer gently for 10 minutes. Serve the sauce with the duck.