1 c. mayonnaise
2 tbsp. vinegar
1 tsp. sugar
1 tbsp. prepared mustard
1 tsp. salt
1/4 tsp. pepper
8 oz. elbow macaroni, cooked and drained
1 c. sliced celery
1 c. chopped green and sweet red pepper
1/4 c. chopped onion

In large bowl, stir together first 6 ingredients until smooth. Add remaining ingredients; toss to well coat. Cover; chill.