In a large bowl combine the cabbage, carrots, onions, scallions, horseradish and garlic. In a small bowl, whisk together the creme fraiche, vinegar, mustard and celery seeds. Toss the slaw with the dressing and season everything with salt and pepper. Marinade the slaw for 1 hour.
Drain as desired, depending on the consistency you are looking for.
Recipe courtesy of Geoffrey Zakarian