Made the best shrimp & fish tacos last night. Here's how it goes:
Cut fish into chunks, about one inch (I used tilapia). Put these in a bowl and season heavily with pepper and seasoned salt (I used Jane's Crazy Mixed-Up Salt). Drizzle with olive oil. Throw in some roughly diced white onion. Fry this in a hot pan for a couple of minutes until just done, do NOT overcook!
Repeat with shrimp. I use the frozen bagged 31-40 shrimp from Costco (thaw out a handful in a bowl of water for 10 min while you're doing other food prep). Season, add oil, add onion, fry it up without overcooking.
Warm up your tortilla, either corn or flour. Add some thinly chopped red cabbage, diced green onion and throw on some of the fish or shrimp with onion (or both, like I did!).
Now add a couple of dollops of the sauce -- low fat sour cream mixed with Asian chili sauce (about 3 parts sour cream to 1 part chili sauce).