Shred 1 medium head green cabbage (about 8 cups)
Thinly slice 1 small onion
In a large bowl, combine cabbage and onion
In a separate bowl, mix 1 cup mayonnaise
Add 2 tbsp apple cider vinegar
Add 2 tbsp sugar (or to taste)
Add 1 tbsp Dijon mustard (optional)
Add 1 tsp salt
Add 1/2 tsp black pepper
Pour dressing over cabbage mixture
Toss until evenly coated
Let stand 15–30 minutes (or refrigerate 2–24 hours) before serving
Optional add-ins: 1 grated carrot, 1/2 cup chopped celery, 1/4 cup chopped parsley