Arrange salad greens on each of 4 plates. Finely chop pears; toss with lemon juice. Divide pear, chopped dates, and chopped walnuts evenly among salads.
Combine olive oil, vinegar, salt, and black pepper, stirring with a whisk.
Drizzle evenly over salads. Top each salad with 1/4 ounce shaved Manchego cheese.