Sprinkle each cod filet with salt, lime, and cayenne. Use your hands to spread the seasonings across each filet, coating as much as possible.
Arrange a dredging station: Place flour in one bowl, the egg in another bowl, and the panko and coconut flakes in a third bowl. Add a pinch of salt to the panko mixture and lightly combine.
Dredge the fish into the flour, then coat completely in egg. Press the cod into the panko mixture, coating each side of the cod completely. Set aside.
Fill a cast iron skillet with ¼ -inch of oil and heat over medium heat until shimmering. To test, add a coconut flake to the oil. If it sizzles and browns, the oil is ready.
Place the cod filets into the skillet, being careful not to crowd the skillet. Cook until crispy and golden brown, about 3-5 minutes per side.
When each side of the cod is golden brown, remove the fish from the skillet and place on a paper-towel lined sheet tray. Serve warm.