In small bowl, combine yogurt, feta, cucumber and mint. Set aside Pat fish dry with paper towels. Season with salt and pepper. Place 1/2 cup potato on top of each fillet, pressing firmly to form an even layer. In large nonstick skillet, heat oil over medium heat until hot. Carefully place fillets, potato side down, in skillet. Cook 8 to 10 minutes (without moving fillets) until potatoes are golden brown. Using large spatula, turn fillets over. Cook an additional 4 to 6 minutes, or until fish is cooked to desired doneness. Serve with sauce and, if desired, lemon and olives.
Makes 4 servings.
Nutrition information per serving: 362 cal., 18 g fat, 75 mg chol., 351 mg sodium, 21 g carbo., 2 g fiber, 27 g pro.