In a medium bowl, whisk together sour cream, mayo, lime juice, garlic powder, and Sriracha until smooth. Let it rest for at least 10 minutes.

Wash and shred purple cabbage. Dice avocado and chop red onion and cilantro. Arrange toppings in small bowls.

Pat shrimp dry and season with minced garlic, sea salt, black pepper, cumin, and cayenne. Toss to coat evenly.

Heat olive oil in a large skillet. Cook the shrimp for 1-2 minutes on each side until cooked through, about 4-5 minutes total.

Warm the corn tortillas in a skillet or over an open flame until pliable.

Assemble tacos by adding shrimp, topping with cabbage, avocado, onion, cheese, and drizzle with creamy sauce. Serve with lime wedges.