1In a large bowl, combine cabbage, onion, carrots, and celery. Sprinkle with 1 cup sugar, and mix well. In a small saucepan, combine vinegar, oil, salt, dry mustard, and pepper. Bring to a boil. Pour hot dressing over cabbage mixture, and mix well.
This is best if made a day ahead to 2 weeks ahead. If you make it far ahead, drain juice prior to serving.