Combine the wine vinegar and broth in a saucepan. Bring to a bail. Stir in the mushrooms. Boil for 2 minutes. Drain, reserving 1/2 cup of the liquid. Cool the mushrooms to room temperature.
Combine the reserved liquid, salad dressing and Italian seasoning in a bowl and mix well. Add the mushrooms and mix gently. Marinate, covered, in the refrigerator for 2 to 10 hours. The flavor of the mushrooms is enhanced with a longer marinating time.