1. Thaw fish, if frozen; cut into 1/2-inch pieces. Set aside.
2. For Green Goddess Sauce, in a blender container or food processor bowl combine yogurt, the 1/4 cup light sour cream, and tarragon. Cover and process or blend until smooth. Transfer to bowl. Stir in remaining 1/4 cup light dairy sour cream, chives, lime juice, and garlic. Cover and chill until serving.
3. In a medium mixing bowl combine egg, bread crumbs, onion, mayonnaise, mustard, parsley, lime peel, and salt. Add fish; mix well. Form mixture into twelve 1/2-inch-thick patties, about 2-1/2 inches in diameter.
4. Coat patties with cornmeal. In a large nonstick skillet or on griddle, heat oil. Add half of the fish cakes. Cook over medium heat for 2 to 3 minutes per side or until fish just flakes when tested with a fork and patties are golden. Repeat with remaining cakes.
For each serving, place three fish cakes on a plate along with 2 tablespoons Green Goddess Sauce. Serve with fish cakes. Cover and refrigerate remaining sauce to use over greens. Makes 4 servings.