In a pan, heat 1 tbsp olive oil over medium heat. Add 1 tbsp garlic and sauté for 30 seconds.
Add 12 oz shrimp, 1/2 tsp black pepper, 1/2 tsp garlic powder, 1/4 tsp ground cumin, 1/4 tsp chili powder, 1/4 tsp salt, 1 tsp paprika, 1/2 tbsp lime juice, and 2 tsp Sriracha to the pan. Stir fry for 2 minutes. Remove the pan from heat.
Add 1 tbsp unsalted butter. Cook and stir occasionally for another 2 minutes.
Bake 8 tortillas at 395 ℉ for 3 minutes.
Make the sauce: In a small bowl, whisk together 4 tbsp mayonnaise, 2 tbsp Greek yogurt, and 1 tbsp chopped cilantro until combined. Set aside.
Assemble the tacos: Fill each tortilla with green cabbage, red cabbage, avocado, stir-fried shrimp, red onions, feta cheese, a drizzle of sauce, and a sprinkle of chopped cilantro. Serve.