In a 12 inch to 14 inch nonstick saute pan, heat oil until smoking. Place 2 fish in pan and saute until golden brown on first side, about 8 to 9 minutes. Turn and cook other side in the same manner. Repeat procedure with remaining 2 fish. Place fish on a serving platter in a warm oven.
In the same pan, add 2 tablespoons more oil, add celery, onion and garlic and cook until soft, about 6 minutes. Add rosemary, vinegar and wine and bring to a boil. Reduce by half, swirl in butter and stir to emulsify. Remove fish from oven. Add parsley to sauce and pour over fish. Serve immediately.
Recipe Courtesy of Mario Batali