Grate the cabbage and onion.

Add 3/4 cup of sugar to the grated cabbage and onion.

Cover the mixture and set aside.

In a separate pot, combine dry mustard, celery seed, oil, vinegar, 1 teaspoon of sugar, and salt.

Bring the dressing mixture to a boil and cook for 2 minutes.

Pour the hot dressing over the cabbage mixture.

Let the slaw set for at least 12 hours.

Refrigerate the slaw before serving.