In a large mixing bowl, combine the finely chopped cabbage, shredded carrot, and onion. Toss together until evenly distributed.
In a separate bowl, whisk together the sugar, vegan mayo, vegan sour cream, lemon juice, and apple cider vinegar until smooth and well combined.
Pour the dressing over the slaw and toss to thoroughly coat.
Taste the slaw and season with salt and pepper if desired.
Cover the bowl with plastic wrap or transfer the coleslaw to an airtight container. Refrigerate for at least 1 hour to allow the flavors to meld together and the coleslaw to get cold.
Notes
To store: Keep copycat KFC coleslaw in an airtight container in the refrigerator for up to 3-4 days. The vegetables will soften over time, so it's best enjoyed within the first 24 to 48 hours for maximum crunch and freshness.