Preheat an indoor or outdoor grill over medium high heat. Drizzle the fish with a touch of olive oil and season it with the chili powder, cumin, paprika, cayenne, salt and pepper.
Grill the fish on the pre-heated grill for 5-6 minutes on each side until fully cooked. The fish should flake easily and there should be a golden brown crust.
Remove the fish from the grill and squeeze the fresh lime juice over the fish. Adjust salt and pepper as needed.
Make the slaw:
Combine all the ingredients together and toss to combine.
To assemble, place a bit of the slaw on the warmed tortilla, followed by few large pieces of the flaked fish, top with the pico de gallo and sliced avocado and drizzle with as much Avocado Tomatillo Salsa as you wish and serve immediately.