Step 1

Add the parsley, yogurt, chives, lemon juice, mayonnaise, tarragon, salt, pepper, garlic and scallion to a blender. Turn the blender on low and gradually increase the speed. Blend until bright green and smooth, about 20 seconds.

Step 2

To assemble, add the torn butter lettuce to a large serving bowl. Drizzle with half the dressing. Serve with extra dressing on the side.