I think this is my third go 'round with the fish taco. The past two times haven't been bad but I have thought of things that I could do better. This time I was really happy with the outcome. the taste came pretty close to Baja Fresh's, a fish taco we really like. I think I really nailed the sauce and I'm not going to mess with it anymore. I used a 50/50 mix of sour cream and plain non-fat yogurt. (1/4c each) I've used mayo in the past. If you google fish tacos, you'll likely see mayo called for in most recipes. But yogurt seems to provide the tang that I'm looking for and a thinner quality that mimics Baja's sauce. Then you need a healthy dose of fresh squeezed lime (a half, juiced) and some chile to your taste. I used a minced red jalapeno and a little of the adobo sauce from a can of chipotles. But the key ingredient gleamed this time was a couple teaspoons of cider vinegar. That's what brought it close to my ideal flavor, which is really tangy. For the fish itself, I used Mahi Mahi which I cut into strips and seasoned with Penzey's adobo spice blend. You could probably just make your own spice mix, but this was an easy way for me. I prefer a "grilled" fish taco as opposed to a fried one. The fried are great, no doubt about it, but this is home cooking we're talking about here. I cooked the fish strips in a non-stick saute pan, browning on both sides and cooking through. Then I kept them warm in a pre-warmed bowl covered with foil while I heated the tortillas. The other key ingredient to a great fish taco is shredded cabbage. We've tried napa, savoy, and plain old green cabbage. And it is the plain old that pleases us most, very thinly sliced. I think it is the cabbage that makes you yearn for a tanginess in the sour cream. It sort of gives you a slaw effect on the taco. Baja Fresh also serves some pico de gallo on the top of theirs. Since it is December in Chicago and fresh tomatoes aren't very good, I used some tomatillo salsa, homemade, for a fresh, hot opposition to the creamy, zingy sauce. We like corn tortillas for our fish tacos. But googling will give you many recipes using flour, so use what you like.