1. Thinly slice the cabbage. Grate the carrots. Chop the onion, if using, very finely.
2. Mix the mayonnaise, cream, vinegar, sugar, salt and pepper in a large bowl.
3. Add the grated vegetables and mix well until they are well coated with the dressing.
4. Cover and refrigerate for at least 1 hour (preferably 3-4 hours) to allow the flavors to blend.
5. Serve chilled as a side dish for fried chicken or sandwiches.
