Preheat oven to 425°.
Leave root and 1-inch stem on beets; scrub with a brush. Place beets on a baking sheet. Bake at 425° for 1 hour or until tender. Cool slightly. Trim off beet roots; rub off skins. Cut beets into 1-inch cubes.
Combine beets and pear in a bowl.
Combine shallots and next 4 ingredients; stir well. Pour over beet-pear mixture, tossing gently to coat.
Divide watercress evenly among 4 salad plates. Spoon beet mixture evenly over watercress. Sprinkle evenly with toasted walnuts.