Garden Salad and Creamy Lemon Dressing

7 cups torn romaine lettuce
2/3 cup thinly sliced seeded peeled cucumber
1/2 cup thinly sliced carrot
1/3 cup sliced green onions
6 cherry tomatoes -- halved
1/2 cup nonfat sour cream
2 tablespoons grated Parmesan cheese
1 1/2 tablespoons lemon juice
1 1/2 teaspoons water
1 1/2 teaspoons vegetable oil
1/4 teaspoon salt
1/8 teaspoon pepper

Combine first 5 ingredients in a large bowl. Combine sour cream and next 6 ingredients (sour cream through pepper) in a small bowl; stir well with a wire whisk. Spoon dressing over salad; toss gently to coat. Yield: 4 servings.