To make fish taco sauce, mix sour cream with mayonnaise, garlic powder, lime juice and Sriracha hot sauce. Whisk all ingredients together in a bowl until smooth.
For an alternative fish taco sauce recipe, use 1/2 cup of reduced fat sour cream or Greek yogurt, 1 cup of mayonnaise, 1 lime cut in half and 1 tablespoon of fresh cilantro. Other ingredients include 1/2 teaspoon of cumin, 1/2 teaspoon of ground coriander, 1/2 teaspoon of dried dill weed, 1/2 teaspoon of dried oregano and 1/2 teaspoon of minced capers. Create a spicier sauce by adding 1 hot pepper and 1/4 teaspoon of ground chipotle chili powder.
Whisk the sour cream and mayonnaise in a bowl until well blended. Squeeze the juice of 1/2 lime into the mixture and continue whisking. The consistency of the mixture should be creamy but easy to pour. If it is too thick, add juice from the other half of the lime. If it is too runny, add more sour cream.
Add all the spices and thoroughly whisk the mixture. Add the minced pepper, capers and cilantro and continue whisking. When you finish, wrap the bowl and refrigerate it for at least one hour. Serve chilled.