This recipe is great warm or room temperature or even chilled. You can make it a day before and store it in the refrigerator. The bit of tarragon adds a little zip to the traditionally mild sauce.
Six 6-ounce, center-cut, skinless salmon fillets
1 cup dry white wine
1 rib of celery, coarsely chopped
1/2 medium onion, coarsely chopped
1 bay leaf
1 tablespoon black peppercorns
2 large egg yolks
1-1/2 tablespoons water
1 tablespoon fresh lemon juice
1/2 teaspoon Dijon mustard
1 tablespoon finely chopped tarragon, plus whole leaves for garnish
1/8 teaspoon cayenne pepper
1 stick unsalted margarine or butter, cubed, at room temperature
PREPARE THE SALMON
Bring a pot of water to a boil. Arrange the salmon fillets in a deep skillet in a single layer. Add the wine, celery, onion, bay leaf and peppercorns and enough of the boiling water to fully cover the salmon. Cook over moderate heat at a bare simmer until the salmon is just firm, about 10 minutes. Transfer the salmon to a platter and pat dry. Sprinkle lightly with salt.
MEANWHILE, MAKE THE HOLLANDAISE
In a heatproof bowl set over a pot of simmering water, whisk the egg yolks with the water, lemon juice, mustard, chopped tarragon and cayenne until slightly thickened, about 2 minutes. Gradually add the margarine/butter, whisking constantly until fully incorporated, about 5 minutes. If the sauce is too thick, whisk in warm water, 1 teaspoon at a time, until the sauce is just pourable. Season with salt.
Spoon the hollandaise over the salmon fillets, garnish with tarragon leaves and serve.