Trim stem and woody greens from cauliflower and cut into about 24 to 30 generous florets/pieces.
Bring a few inches of water to a boil in a deep skillet or pot. Salt the water and cook cauliflower 1-2 minutes; remove with a spider and cold-shock to stop the cooking process. Drain and dry on a kitchen towel.
Heat oil in a Dutch oven or tabletop fryer to 360°F.
In a large mixing bowl, whisk together flour, 1 teaspoon salt, cornstarch, baking powder and granulated garlic and onion; stream in beer while whisking to combine.
Dunk pieces of cauliflower in the batter and place gently in the hot oil. Cook 6-8 florets at a time so as not to overcrowd the oil. Fry to deep golden brown then drain on a wire rack-lined sheet tray in a warm (275°F) oven. Repeat until all of the cauliflower pieces are cooked.
Heat a sauté pan over medium heat, add butter and melt. Add garlic, swirl a minute, then add hot sauce and Worcestershire, if using; swirl a minute more.
Transfer cauliflower to a large bowl, douse with sauce and toss to coat. Serve on a platter garnished with chopped celery greens.