In a large bowl, add the coleslaw, chopped apples, and shallot; sprinkle lightly with salt, toss, then set aside. In a small bowl, whisk together the apple cider vinegar, fine sugar, honey, and celery seed, then slowly drizzle in the oil until the sugar dissolves and the dressing emulsifies. Pour the dressing over the coleslaw and apple mixture, then toss gently until everything is coated. Cover and refrigerate for 30 minutes, then toss again, add salt and pepper to taste, and serve cold.