Prepare the Green Goddess Dressing: Combine the mayonnaise, sour cream/yogurt, parsley, tarragon, lemon juice, minced garlic, anchovy paste (if using), salt, and pepper in the bowl of a food processor or high-speed blender.

Blend the dressing until it is completely smooth and vibrant green. Taste and adjust seasoning, adding more lemon juice for tang or salt/pepper as needed. If the dressing is too thick, add 1-2 tablespoons of cold water until desired consistency is reached.

Prepare the salad base: Place the chopped iceberg lettuce in a large chilled serving bowl.

Add the thinly sliced radishes and half of the chopped chives to the lettuce. Keep the salad components chilly for maximum crispness.

Dress the salad immediately before serving. Drizzle about half of the Green Goddess dressing over the lettuce mixture and gently toss until the lettuce leaves are evenly coated. Add more dressing as preferred, but be careful not to over-dress.

Divide the salad onto plates. Garnish the top of each serving with the remaining fresh chives and the toasted pecans or walnuts.