Finely chop the shredded cabbage and carrots. Set aside.
In a large mixing bowl, whisk together the vinegar, sugar, mustard powder, and salt until the sugar is dissolved.
Whisk the mayonnaise into the vinegar mixture.
Add the cabbage and carrots into the sauce and stir to combine.
Refrigerate for 2 hours until cold and serve.
Notes
You could stretch one batch out to 8 servings.They did not indicate what type of vinegar, however I would assume white distilled. Apple cider would also work but brings a little flavor with it.