Chop pears into small bite-sized pieces and place into a bowl. Sprinkle well with a little lemon juice, stir to cover to keep from browning. Set aside.
In a large salad bowl, combine the Spring mix greens, red onion, walnuts, raisins, blue cheese and the pears. Top with balsamic vinaigrette dressing and mix well. Serve immediately. Makes 6 servings. Enjoy!