To make the dressing, put all the ingredients in a small food processor and process until smooth and creamy. Taste it to adjust any of the flavors. Pour into a small jar and refrigerate until needed. This can be done up to a day or two in advance, it just gets better! Double or triple the recipe for larger amounts.
Slice off the core ends of the heads of lettuce and wash and dry the leaves well. I like to keep them whole for this salad. Arrange them in a wide shallow salad bowl, covering the whole surface of the bowl.
Arrange the rest of the ingredients on top of the lettuce. Season with fresh cracked black pepper, and drizzle with the dressing just before serving.