For an extra layer of flavor, try toasting the walnuts with a pinch of sea salt and a dash of maple syrup. A balsamic vinaigrette or a creamy poppy seed dressing complements this salad beautifully. For a lighter option, a simple lemon vinaigrette also works wonders. If you don't have feta cheese on hand, goat cheese or even a mild blue cheese can be substituted. To prevent the lettuce from wilting, dress the salad just before serving.