Food & Wine and Ina Garten both offer recipes for dill sauces that pair well with fish. Food & Wine's recipe is a basic mayonnaise-based dill and lemon sauce, while Ina Garten's recipe includes these ingredients as well as sour cream, yogurt, cream cheese, scallions and parsley.
To make the Food & Wine dill sauce recipe, whisk 1 cup of reduced-fat vegan mayonnaise or regular mayonnaise in a bowl with 2 tablespoons of fresh lemon juice and 1/4 cup of chopped fresh dill. Season to taste with sea salt, and refrigerate until ready to serve. Serve with foods such as fish cakes or steamed vegetables.
For Ina Garten's fresh dill sauce recipe, place 1/2 cup of high-quality mayonnaise, 1/2 cup of sour cream, 1/2 cup of plain yogurt, and 2 tablespoons of room-temperature cream cheese in a food processor. Add 1/2 cup of chopped scallions, 1/2 cup of minced fresh dill, 1/4 cup of minced fresh flat-leaf parsley, 1 teaspoon of grated lemon zest, and 2 tablespoons of freshly-squeezed lemon juice. Add 2 teaspoons of kosher salt and 1 teaspoon of freshly ground black pepper, then puree for a few seconds until combined. Add 1 cup of seeded and grated hothouse cucumber to the food processor and blend for a few seconds until combined. Transfer to a container and refrigerate for a few hours prior to serving.