Place the flour into a shallow dish. Season chicken with salt and pepper, and then dredge in flour. Shake off excess. Heat the butter in a large skillet over medium-high heat. Brown the chicken breasts on each side, about 3 minutes per side.Advertisement
Pour the chicken broth and white wine into the skillet, and scrape any chicken residue from the pan for flavor. Stir in the mustard. Cover, and cook for a few minutes until chicken is 'springy', but not cooked through. Add the zucchini and sun-dried tomatoes, then season with garlic and dill weed. Cover, and cook until the zucchini is tender and the chicken is cooked through, about 5 to 10 minutes.
Remove the chicken to a platter, and remove the pan from the heat. Stir sour cream into the pan liquid. If most of the liquid has evaporated, stir in a bit more wine or broth first. Season with salt to taste, and serve chicken with sauce poured over it.