Cook macaroni according to package directions, except omit the oil and cook in light salted water. Drain well. Rinse with cold water;drain again.

For dressing, in a salad bowl stir together sour cream, mayonnaise dressing, mustard, 2 teaspoon of the milk, and the black pepper.

Stir the cooked macaroni, sweet pepper, carrot and green onion into the dressing. Toss lightly to coat. If desired, gently stir in cheese. Cover and chill for at least 3hours or up to 24 hours. Before serving, stir in the remaining milk if necessary to moisten salad.