I'm told there are healthy versions of this using grilled swordfish in southern California, but I'm going for the fried version here.
I take tilapia or catfish fillets, dredge them in seasoned flour, dip them in beaten egg, and then dredge them through panko, a large flake Japanese bread crumb (which makes a lighter crust).
Next, I saute the fillets. Bacon fat is really good here, but any oil would work well. For either of the thin fillets allow about 3 minutes per side. Be careful flipping them, they may come apart.
I make a sauce out of adobo (smoked jalapenos in adobo sauce from Reyna's in the Strip District) whizzed together with mayonnaise and ketchup in my little handheld food processor. (A little of this goes a long way.)
I then shred cabbage and mix it with lime juice, a little olive oil, and some S and P.
I spread a little sauce on a heated flour tortilla (place them in a hot ungreased cast iron skillet for 20 seconds/side), top it with fried fish, add some cabbage, some chopped cilantro if you have it... voila.