Blend vinegar and mustard. Gradually add oil, pouring in thin stream and beating until mixture thickens slightly. Add wine and season to taste with salt and pepper. Toss mushrooms with lemon juice. Add parsley, chives and vinaigrette. Toss, chill, then toss again before serving. Garnish with tomato slices.

This recipe yields 6 servings.

Each serving: 348 calories; 173 mg sodium; 0 cholesterol; 38 grams fat; 5 grams carbohydrates; 3 grams protein; 0.63 gram fiber.