Several grinds of pepper Rinse the fillets and place in a shallow pan large enough to hold them in one layer. Add the champagne, lemon juice, and enough water to just cover the fillets. Remove the fish and bring poaching liquid to a boil. Lay the fish back in the pan in a single layer and top with the onion slices, capers, tarragon, and pepper. Reduce heat to low, cover, and simmer 4 to 6 minutes, depending on the thickness of the fish. Fish is done when mostly opaque but still barely transparent at the very center. Remove fish from the liquid, along with onions, capers, and tarragon. Drain well and serve immediately on warmed plates. This is nice with a wild rice pilaf and a tossed green salad. Each serving provides: Calories 256, protein 29 g, carbohydrate 5 g, sodium 102 mg, cholesterol 105 mg, fat 5 g, 19% of calories from fat.