Step 1

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.

Step 2

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 made1 day ahead. Cover; keep refrigerated.)