Light Tartar Sauce
What's crispy, crunchy fried fish without tartar sauce? But it makes no sense to use a full-fat tartar sauce with our oven-fried fried fish. We found that a combination of reduced-fat mayonnaise and low-fat sour cream with piquant cornichons, capers, and red onion made a perfect dipping sauce.

Makes about 1/2 cup 
1/4 cup reduced-fat mayonnaise 
3 large cornichons, minced (about 1 1/2 tablespoons) 
2 teaspoons cornichon pickling juice 
2 tablespoons minced red onion 
1 tablespoon capers, rinsed and minced 
Salt and ground black pepper 
Water 
Mix all ingredients together, adding water as needed to thin the sauce out. Cover and refrigerate until the flavors blend, about 30 minutes. (The sauce can be refrigerated for several days.)
(From The Best Light Recipe)