In a large bowl combine cooked pasta, mixed vegetables, kidney beans, celery, cucumber, green pepper and onion.
To make the dressing combine in a saucepan over medium heat: vinegar, margarine, sugar, flour, salt and brown mustard; bring to boil. Continue to cook for 5 minutes stirring frequently. Cool completely.
Pour cooled dressing over bowl of vegetables. Toss to distribute dressing evenly. Cover tightly and store in refrigerator.