Preparation Stir together 2 tablespoons sour cream with water, anchovies, and garlic in a small saucepan, then cook at a bare simmer, whisking frequently, 10 minutes. Force through a fine-mesh sieve into a bowl. Whisk in mayonnaise, 1/2 teaspoon pepper, 1/4 teaspoon salt, remaining cup sour cream, and lemon juice (to taste). Chill, covered, at least 1 hour and up to 2 days. While dip chills, blanch beans in 3 quarts boiling water with 1 tablespoon salt 1 minute, then drain and immediately chill in an ice bath 5 minutes. Drain well and pat dry. Serve with dip. Cooks' note:Beans can be blanched 1 day ahead and chilled, wrapped in dampened paper towels, in a large sealable plastic bag.
Preparation Stir together 2 tablespoons sour cream with water, anchovies, and garlic in a small saucepan, then cook at a bare simmer, whisking frequently, 10 minutes. Force through a fine-mesh sieve into a bowl. Whisk in mayonnaise, 1/2 teaspoon pepper, 1/4 teaspoon salt, remaining cup sour cream, and lemon juice (to taste). Chill, covered, at least 1 hour and up to 2 days. While dip chills, blanch beans in 3 quarts boiling water with 1 tablespoon salt 1 minute, then drain and immediately chill in an ice bath 5 minutes. Drain well and pat dry. Serve with dip. Cooks' note:Beans can be blanched 1 day ahead and chilled, wrapped in dampened paper towels, in a large sealable plastic bag.