1. combine sour cream, 2 Tbs dill, 2 Tbs vinegar, shallots, rind, juice, and garlic in a bowl, stirring well; cover and chill.
2. sprinkle fish evenly with salt and pepper. heat a large nonstick skillet over medium-high heat. coat pan with cooking spray. add fish to pan, and cook for 3 minutes. turn fish over, and cook 1 minute. remove from heat. add wine; cover and let stand 3 minutes or until fish flakes easily when tested with a fork or until desired degree of doneness.
3. using a vegetable peeler, shave cucumber lengthwise into ribbons to yield about 2 cups. combine cucumber, remaining 1 Tbs rice vinegar, and remaining 1 tsp dill in a bowl; toss gently to coat. place about 1/2 cup cucumber mixture on each of 4 plates; top each serving with 1 fillet and 2 Tbs sour cream mixture