1. Whisk the olive oil and vinegar together.
2. Season with salt and pepper; set aside.
3. Using a mandolin, slice the pears lengthwise and place them in a shallow pan; coat with lemon juice.
4. Arrange the pear slices on a plate.
5. Toss the salad greens with the dressing and arrange in a pile alongside the pear.
6. Add a sprinkling of walnuts and blue cheese.
7. Serve immediately.