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

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