Combine all ingredients in dressing list: mayonnaise, vinegar, sugar, mustard, salt, pepper, celery seeds, Tabasco Sauce, and garlic powder. Whisk until smooth and incorporated well. Set aside.
Slaw
Combine package of slaw, finely chopped red cabbage, thinly sliced red onion. Toss together. Add dressing, and combine using tongs. Finally add Mandarin oranges and carefully fold in with a spatula as to not break up oranges.
Refrigerate for minimum of one hour before serving.
NOTE: Do not mix dressing with slaw more than three hour before serving, slaw looses it's crunch the longer it sits in the dressing, and you want that texture.