Add all of the ingredients for the orange salsa to a bowl and stir well. Set aside until ready to use.
Drizzle the fish with about 1 tablespoon of olive oil and use your hands to smear it over the full surface of the fish. In a small bowl, stir together the seasonings and sea salt. Sprinkle the seasoning mixture over the fish (it's okay if you don't use all of it). If marinating for a long period of time, place fish in a zip lock bag and refrigerate until ready to cook.
Add the remaining olive oil (to a cast iron skillet and heat to medium-high. Once the skillet it fully hot, place the fish on it, skin-side up. Cook 3 to 5 minutes, or until golden-brown and crispy. Flip and cook an additional 3 to 5 minutes, or until the fish is cooked through. (If using white fish, you can tell the fish is fully cooked when it's opaque, or the internal temperature reaches 145 degrees F).
Heat the tortillas and load them up with desired amount of avocado slices, fish and orange salsa. Top with sliced radishes and fresh cilantro, and serve!