Winter greens with cranberry vinaigrette

1/2 cup cranberry juice cocktail
2 tablespoons salad oil
1 tablespoon red wine vinegar
1 teaspoon sugar
1/2 teaspoon salt
1 small head romaine or leaf lettuce
1 head Belgian endive
1 cucumber, thinly bias-sliced
1 cup fresh enoki mushrooms or sliced button mushrooms (3-1/2 ounces)
1 red sweet pepper, cut into thin bite-size strips
1/2 cup alfalfa sprouts, optional
Lemon juice
1 avocado

1. For dressing, in a screw-top jar combine cranberry juice cocktail, oil, vinegar, sugar, and salt. Cover and shake well. Chill until serving time.
2. Meanwhile, rinse romaine and endive; pat dry. Line a platter with some of the romaine and all of the endive. Coarsely shred remaining romaine; spread over platter. Arrange cucumber, mushrooms, red pepper, and sprouts, if desired, on lettuce-lined platter. If desired, cover and chill for up to 24 hours.
3. To serve, halve, seed, peel, and thinly slice avocado, brushing slices with lemon juice. Add avocado to platter. Shake dressing well and serve with salad.