Zest the lemons and chop. Squeeze the juice through a strainer. Reserve 2 Tbsp. of zest and ¼ c. of juice.
Place the sour cream, mayonnaise, lemon zest and juice, parsley, basil, chives, granulated onion and garlic, salt and white pepper in a stainless steel mixing bowl. Whisk together thoroughly.
Purée the dressing ingredients in batches using a blender. Once each batch is smooth, place in a stainless steel mixing bowl and whisk together. Place in a covered storage container and refrigerate until needed.