Preheat your oven to 400°F and line a baking sheet with parchment paper.
Gently cut the cauliflower down the middle about 1–2 inches deep, keeping the base intact so it stays in one piece.
In a small bowl, whisk together the avocado oil, red curry paste, chili powder, and garlic powder. Brush this mixture all over the cauliflower.
Place the cauliflower on the baking sheet and roast for 20 minutes.
While it bakes, mix the sour cream, 2 tbsp mayonnaise, 3 tsp Thai chili garlic sauce, apple cider vinegar, and 2 tsp sweetener in a bowl. After 20 minutes, spread this mixture over the cauliflower and bake for 10 more minutes.
In another small bowl, combine the remaining ¼ cup mayonnaise, 1 tsp Thai chili garlic sauce, and 1 tsp sweetener. Spoon this into a small sandwich bag, snip a tiny corner off, and set aside.
Remove the cauliflower from the oven. Drizzle the mayo mixture from the bag over the brain, then add Sriracha on top.
Garnish with fresh cilantro, crushed pork rinds, and chopped scallion. For a spooky effect, serve on a stand with a knife stabbed into the top.