How to Make It
Preheat oven to 450°F. Heat 1 tablespoon of the olive oil in a medium skillet over medium-high. Add chorizo and cook, stirring occasionally, until crispy, 4 to 5 minutes. Remove chorizo with a slotted spoon, and drain on paper towels.
Heat 1 tablespoon of the olive oil in a medium saucepan over medium-high. Add onion and cook, stirring often, until tender, about 3 minutes. Stir in garlic and cook, stirring constantly, 30 seconds. Add tomatoes, sherry vinegar, and cayenne pepper; cook, crushing tomatoes with a wooden spoon, 10 minutes. Remove from heat; cool 5 minutes. Spoon mixture into a food processor, and process until smooth. Add mayonnaise, and process 30 seconds. Set aside.
Toss together cauliflower florets, smoked paprika, salt, and remaining 1 tablespoon olive oil in a large bowl. Spread in a single layer on a parchment paper-lined baking sheet. Bake in preheated oven until tender, about 10 minutes. Increase temperature to broil. Broil until slightly charred and crispy, 1 to 2 minutes. Transfer to a serving platter.
Drizzle cauliflower with tomato mayonnaise. Top with crispy chorizo and scallions, and serve immediately.