Prepare the Cauliflower: Wash the cauliflower and dry it thoroughly. Cut it into evenly sized, bite-sized florets so they cook at a similar rate. Remove any excess moisture with a clean kitchen towel.
Season the Florets: Place the cauliflower in a large bowl. Add olive oil, chili powder, cumin, smoked paprika, garlic powder, onion powder, salt, and black pepper. Toss until every piece is evenly coated.
Preheat the Air Fryer: Preheat the air fryer to 390°F for about 3 minutes, if your model requires preheating. Lightly grease the basket or use an air fryer-safe liner with enough space for air circulation.
Air Fry the Cauliflower: Arrange the seasoned florets in a single layer in the basket. Cook at 390°F for 12–15 minutes, shaking the basket halfway through, until the cauliflower is tender and has golden, crispy edges. Cook in batches if necessary.
Prepare the Creamy Sauce: While the cauliflower cooks, whisk together the sour cream or Greek yogurt, lime juice, garlic powder, and salt in a small bowl. Add water gradually until the sauce reaches a smooth, drizzle-friendly consistency.
Warm the Tortillas: Heat the tortillas in a dry skillet for about 20–30 seconds per side or warm them briefly in the microwave. Keep them covered with a clean towel to prevent them from drying out.
Assemble the Tacos: Divide the shredded cabbage among the warm tortillas. Add the air-fried cauliflower, diced tomatoes, and avocado slices. Drizzle with the creamy sauce.
Garnish and Serve: Finish with chopped cilantro and a squeeze of fresh lime juice. Serve immediately while the cauliflower is warm and crisp.