In a bowl, combine ½ cup sour cream, 2 tablespoons fresh lemon juice, and 2 tablespoons mayonnaise.
Add 1 tablespoon chopped fresh basil and 1 teaspoon Dijon mustard to the mixture.
Season the dressing with salt and pepper according to your taste.
Whisk the ingredients together until the dressing is smooth and well combined.
Refrigerate the dressing for at least 1 hour before serving for optimal flavor.