Season pork with salt and pepper. Heat oil in a large nonstick skillet over medium-high heat. Add pork and cook until browned and just cooked through, 2 to 3 minutes per side. Transfer to a plate and keep warm. Pour off fat from the pan.
Add vinegar and sugar to the pan; stir to dissolve the sugar. Cook over medium-high heat until the syrup turns dark amber, 10 to 20 seconds. Pour in wine (stand back, as the caramel may sputter) and bring to a simmer, stirring. Add broth, pears and ginger; bring to a simmer. Cook, uncovered, turning the pears occasionally, for 5 minutes. Add scallions and cook until the pears are tender, about 2 minutes more. Add the cornstarch mixture and cook, stirring, until lightly thickened. Reduce heat to low and return the pork and any accumulated juices to the pan; turn to coat with the sauce. Serve immediately.