For the dressing:
1/3 cup mayonnaise
1/4 cup sour cream
1/4 cup finely chopped fresh parsley
2 tablespoons finely chopped fresh chives
1 tablespoon minced scallions
1 tablespoon tarragon vinegar
2 teaspoons fresh lemon juice
3 anchovy fillets, minced
4 salmon fillets (with skin), 6 to 8 ounces each and about 1 inch thick
Freshly ground black pepper
Extra-virgin olive oil
1. To make the dressing: In a food processor blend the dressing ingredients together.
2. Season the flesh side of the salmon fillets with salt and pepper to taste. Generously brush or spray the flesh with olive oil. Grill the fillets, flesh side down, over Direct Medium heat until you can lift them with tongs off the grate without sticking, 7 to 8 minutes. Turn the fillets and finish cooking them, skin side down, for 2 to 3 minutes. Slide a spatula between the skin and flesh, and transfer the fillets to serving plates. Spoon the dressing over the fillets. Serve immediately.