Bake pecans in a shallow pan at 350°, stirring occasionally, 10 to 15 minutes or until toasted.
Process garlic in a blender until chopped; add sour cream, lemon juice, and sugar, and process until blended. With blender running, add oil in a slow, steady stream.
Arrange watercress, pecans, cheese, and blueberries on 6 individual salad plates. Serve with dressing, and garnish, if desired.
