Step 1 In a blender, pulse together the parsley, basil, chives and spinach along with the cider vinegar. Remove the mixture to a large bowl and whisk in the mayonnaise, mustard, salt, pepper and lemon juice. Taste and adjust the flavorings and seasonings as desired. This makes a generous 3 cups of dressing, which will keep, covered and refrigerated, up to 1 week.