I am still trying to come up with the right sauce to top my fish tacos with, but here is what I do so far:
Fresh filets: milder is better (I prefer snapper, grouper, and trout over tunas, mackerals or any other oily fish)
Season the fish with a southwestern style seasoning (Emerils Southwestern essence, or Penzy's southwestern will do well here) and dredge in a seasoned (use the same seasoning) cornmeal-flour mixture (60-40) and fry in vegetable or canola oil at 350 deg. until fish is done.
Serve on warm tortillas and use the toppings below:
I make a salad/pico that I use as a topping:
2 cups shredded iceberg lettuce
2 cups fine julienne cut purple cabbage
1/2 cup chopped onion
1/4 cup chopped tomatoes
1/2 cup chopped cilantro
1/2 cup diced avocado
1 tablespoon fine chopped jalepeno
Of course, you can adjust the ingredients to your taste.
Make a simple lime vinegrette using 4 tablespoons olive oil, 2 tablespoons lime juice and 1 tablespoon of champagne vinegar, a teaspoon of fine chopped cilantro and a dash of salt. Use enough of this dressing to lightly coat salad/pico.
I usually finish my fish tacos with a green salsa similar to Ninfas origonal green sauce. I have also made sauces based on fat free plain yogurt flavored with lime juice, garlic and chipotle peppers. Like I said, I am still searching for the best one, but it is important to not add too many flavors. The fresh fish and vegetables dressed with lime is about all you need.