Carolina Cole Slaw

from epicurious:

1/2 cup distilled white vinegar
6 tablespoons sugar
6 tablespoons vegetable oil
2 1/2 teaspoons dry mustard
1 teaspoon celery seeds

1 medium cabbage (about 1 1/4 pounds), thinly sliced
1 large onion, thinly sliced
1 large green bell pepper, thinly sliced

Combine vinegar, sugar, oil, mustard and celery seeds in nonaluminum medium saucepan. Stir over medium heat until sugar dissolves and dressing comes to boil. Remove from heat. Season with salt and pepper. Cool completely.

Combine cabbage, onion and green pepper in large bowl. Add dressing; toss to coat. Cover; refrigerate until cold, tossing occasionally, at least 2 hours. (Can be made
1 day ahead. Cover; keep refrigerated.)