Creamy herb dressing

1 cup plain yogurt;

1⁄2 cup sour cream;

1⁄4 cup fresh lemon juice;

1⁄2 cup chopped flat-leaf parsley;

2 tablespoons chopped fresh dill;

2 tablespoons chopped fresh chives;

2 tablespoons chopped fresh basil;

3 garlic cloves, chopped;

1 tablespoon wholegrain Dijon mustard;

11⁄2 teaspoons drained and finely chopped anchovies or anchovy paste;

1⁄3 cup extravirgin olive oil;

1 teaspoon kosher salt, or to taste;

1⁄2 teaspoon ground black pepper, or to taste.

Use soon or cover and refrigerate for up to 5 days. Return to room temperature, stir well, and check the seasoning before serving.