For dressing, in a screw-top jar, combine olive oil, balsamic vinegar, and salt. Cover and shake well. Set aside.
In a large skillet, cook pancetta or bacon over medium heat until crisp. Remove from skillet; drain on paper towels. Set aside. Add pear slices to drippings in skillet; cook for 5 to 7 minutes or until lightly browned and tender, stirring occasionally. Keep warm.
In a very large bowl, combine arugula, onion slices, and dressing. Gently toss to coat with dressing.
Divide arugula mixture among six salad plates. Arrange pears on top. Sprinkle with pancetta, pine nuts, and Gorgonzola cheese. If desired, sprinkle with freshly ground black pepper. Makes 6 side-dish servings.