add water until you have the consistency of a dressing (maybe a little lemon to taste)
variation (of Cathy's recipe Sarah):
add tomato sauce, lemon juice, cumin and sour salt. The sour salt gives it a vinegary taste. Use salad greens like baby spinach and romaine that have more flavor than iceberg lettuce. Also, you can chop up an apple or orange for some added sweetness.