Poached Salmon with Beurre Blanc

POACHING SMALL FISH or fish fillets is a quick technique used in French restaurants. Although classically such a dish would be made by poaching the fish in a court bouillon (light vegetable stock), I find the use of court bouillon advantageous only when poaching fish to be served cold (see Cold Poached Salmon with Green Mayonnaise). So I just poach fish fillets (salmon as here, or another thick fish such as sea bass or striped bass) in water, sometime