1. Preheat oven to broil.
2. In a medium bowl, stir together vinegar, brown sugar, ginger, and 1/4 teaspoon of salt until the sugar is dissolved; remove 1/4 cup. Add the cucumbers to the remaining vinegar mixture; toss.
3. Spray an unheated broiler pan with nonstick cooking spray. Arrange fish on the rack; brush with reserved vinegar mixture. Broil 4-6 minutes or until fish flakes easily.
4. In a bowl, combine the yogurt and mint. With a slotted spoon, add the cucumbers to plates. Top with the fish, yogurt, some lemon peel, if available, and ground black pepper.
