In 2-quart saucepan, cover sliced potatoes with salted water. Heat to boiling. Cover and reduce heat. Simmer 8 to 10 minutes or until potatoes are almost tender. Drain; set aside.
Meanwhile, in 12-inch nonstick skillet, heat oil over medium-high heat. Saute mushrooms and onion 7 minutes or until mushrooms are soft and onion is tender. Stir in pears, cooked potatoes and sage. saute 3 to 4 minutes longer or until potatoes are tender. Stir in broth, vinegar, salt and pepper. Cook and stir 1 to 2 minutes longer or until broth is reduced slightly. Garnish with sage leaves.