Do ahead:

1 head cabbage, chopped
1 green pepper, chopped
1/2 c. vinegar
1/2 c. salad oil
1 tbsp. salt
1 lg. onion, sliced thin
1/2 c. sugar
1 tsp. dry mustard
1 tsp. celery seed
1 tbsp. sugar

Layer cabbage, onion and pepper in bowl. Pour 1/2 cup sugar on top. Boil vinegar, salad oil, salt.