Step 1

Place cabbage in a very large bowl; toss with salt. Let stand 1 hour.

Step 2

Meanwhile, in a large saucepan, combine sugar, water, vinegar, celery seed and mustard seed. Bring to a boil, stirring to dissolve sugar. Cook 1 minute. Remove from heat; cool slightly.

Step 3

Drain excess liquid from cabbage, if necessary. Add red peppers and carrots to cabbage. Add dressing; toss to coat. Cool completely. Transfer to freezer containers. Freeze, covered, up to 3 months.

Step 4

To serve, thaw coleslaw overnight in refrigerator. Stir before serving.