"Sauce is the making of a fish taco, and I've never been happy with my efforts," laments lifespan. Hounds recommend various easy-to-make sauces, and especially love creamy sauces spiked with lime and made smoky and spicy with chipotles. They use yogurt, sour cream, and mayonnaise as a base, alone or in combination.
juli5122 makes a sauce of equal parts mayonnaise and sour cream, plenty of chopped cilantro and green onion, and lime juice, salt, and pepper to taste. trees305 used to work at a restaurant that specialized in Ensenada-style fish tacos, and they used mayonnaise thinned with evaporated milk, and "juice to taste from a jar of pickles. ... The pickle juice adds a nice twang to the sauce."
"I've made homemade sauces, but keep coming back to a nice mix of Marie's Creamy Chipotle Ranch dressing thinned out with some freshly squeezed lime juice," says Isolda. "We call this 'chipotle crack.'" Out of time on a weeknight, egbluesuede tried this combo, and says, "The family LOVED it."