Pat the shrimp very well and transfer to a medium bowl. Add the olive oil, lime zest, chili powder, cumin, garlic and salt and stir to combine. Cover and refrigerate shrimp for 15 minutes.
Meanwhile, make the slaw. In a large bowl, combine cabbage, lime juice, mango, jalapeño, cilantro and salt. Cover and refrigerate for 15 minutes.
Once the shrimp have marinated, thread them onto the prepared skewers. Set aside while you preheat the grill. If using a grill pan, grease lightly with a high-heat oil, then preheat for 3 minutes over medium heat. Add shrimp and cook for 2 to 3 minutes per side, or until cooked through. If using a gas grill, preheat to medium, then grill the shrimp skewers for 2 to 3 minutes per side with the lid open.
Warm the tortillas on the grill pan or gas grill for 10 seconds per side. To serve, place 3 shrimp into each tortilla. Top with a generous mound of slaw and a few slices of avocado and serve.
Notes
Storage: Store leftover grilled shrimp and slaw in separate airtight containers for up to 3 days. Reheat shrimp gently in a frying pan over medium heat or in the microwave. Tips:Skewer shrimp properly. Skewering shrimp makes them easier to handle on the grill and eliminates the need to flip individual shrimp. It also reduces the risk of them falling through the grates and ensures even cooking. If using wooden skewers, soak them first in water for about 10 minutes to help prevent them from burning or splintering during threading.Zest first, then juice the lime. Capture the bright and aromatic oils in the lime zest first, then proceed to juicing it. It's nearly impossible to zest a lime after it has been squeezed so do that step first.If using a grill pan: grease lightly with a high-heat oil like avocado or canola oil to prevent the shrimp from sticking. Preheat for a few minutes over medium heat, then add the shrimp.Don't overcook the shrimp. Depending on the size of the shrimp, time may vary slightly but shrimp, like most seafood, cooks fast. So keep your eye on it and as soon as it's opaque pink, take it off the heat.