Hearts of palm were once a high-end delicacy popular in the early 1900s at some of Florida's more luxurious hotel restaurants. During the Great Depression, however, widespread consumption threatened to wipe out the state's palmetto trees from which hearts of palm are harvested.
Today, palmettos are grown as a cash crop and the hearts harvested when the trees reach a height of five feet. Only in Florida can you find fresh hearts of palm; elsewhere, they are sold canned and packed in water.
Place the first 6 ingredients in a small bowl. Sprinkle with the salt and add the olive oil. Stir thoroughly while adding the vinegar. Keep in the refrigerator. Always stir before using.
Place the lettuce flat on a dish. Arrange the hearts of palm in a row. Arrange the pimiento across the lettuce and decorate at the side with watercress. Serve with vinaigrette dressing.