Preheat oven to 425F.
Add cauliflower to mixing bowl.
Add cayenne pepper sauce, pepper, and panko to the bowl of cauliflower and stir.
Pour onto a baking sheet.
Bake for 15 minutes.
Put Spinach in a bowl, top with vinegar.
Place red onions and celery on top of spinach.
When cauliflower is done baking, toss in a bowl with extra cayene pepper sauce if desired.
Pour cauliflower on top of spinach and serve.