In a small screw-top jar, combine oil, balsamic vinegar, and salt. Cover and shake well. Set aside.
In a large skillet, cook pancetta over medium heat until crisp. Drain pancetta on paper towels, reserving drippings in skillet. Add pears to the reserved drippings. Cook for 5 to 7 minutes or until pears are tender and lightly browned, stirring occasionally. Remove from heat; cover and keep warm.
In a very large bowl, combine arugula and red onion. Shake dressing. Pour dressing over arugula mixture; toss gently to coat.
Divide arugula mixture among six salad bowls or plates. Arrange pears on top. Sprinkle with pancetta, cheese, pine nuts, and, if desired, pepper.