In a large bowl, combine the mayonnaise, vinegar, honey, salt and pepper. Whisk until smooth and well combined.
Add the cabbage, carrots and onions, and toss everything to coat. Cover and refrigerate for at least 30 minutes. Toss, taste for seasoning and adjust with salt, pepper or honey, as desired. For best results, refrigerate overnight. Can be stored, covered, for up to 5 days in the fridge.