1. Prepare the garlic cilantro lime sauce: In a food processor or blender, pulse oil, green onions, cilantro leaves, garlic cloves, salt, lime juice, and sour cream (or Greek yogurt) until mostly smooth. Add water as needed to reach desired sauce consistency. Reserve some sauce for drizzling and toss some with shredded cabbage to make a creamy slaw.

2. Make the slaw: Combine shredded green cabbage, thinly sliced red onion (if using), sliced or smashed avocado, and the prepared sauce. Toss gently to coat well. Adjust seasoning as needed.

3. Season the shrimp: Pat the shrimp dry with paper towels. In a small bowl, mix chili powder, cumin, garlic powder, onion powder, cayenne, salt, black pepper, and smoked paprika. Toss the shrimp in the spice mix until evenly coated.

4. Cook the shrimp: Heat olive oil in a skillet over medium-high heat. Add shrimp in a single layer and cook 5 to 8 minutes, flipping occasionally, until pink and cooked through with slight caramelization.

5. Warm the tortillas: Lightly warm tortillas over a gas flame, in a dry skillet, or in the oven to make them pliable and add a slight char if desired.

6. Assemble the tacos: On each tortilla, layer smashed avocado, slaw, cooked shrimp, and a sprinkle of Cotija cheese. Drizzle with remaining garlic cilantro lime sauce and serve with lime wedges on the side.