Preheat the oven to 425 degrees F. Toss the hash browns with the garlic and 1 teaspoon salt in a bowl. Heat 2 tablespoons olive oil in a large nonstick ovenproof skillet over medium heat. Add the hash browns, flatten with a spatula and cook until the bottom is golden brown, 6 to 8 minutes. Drizzle with 2 tablespoons olive oil. Flip the potato cake and pat it back into shape. Cook until crisp and golden, 6 to 8 minutes.
Meanwhile, mix the olives, tomatoes, roasted peppers, scallions and parsley in a bowl. Cut the fish into 12 pieces and season with the dried herbs, salt and pepper. Scatter half of the olive mixture over the potato cake and top with the fish.
Scatter the remaining olive mixture on top and drizzle with the remaining 1 tablespoon olive oil. Transfer the skillet to the oven and bake until the fish is cooked through, about 12 minutes. Drizzle with olive oil and season with salt. Serve from the skillet.
Per serving: Calories 443; Fat 19 g (Saturated 3 g); Cholesterol 85 mg; Sodium 937 mg; Carbohydrate 32 g; Fiber 4 g; Protein 37 g