Trim fat from chops. Coat a large nonstick skillet with cooking spray; place over high heat until hot.
Sprinkle chops with sage, salt, and pepper; add to skillet, and cook 1 minute on each side. Reduce heat to medium; cook chops 4 to 5 additional minutes on each side or until done.
Transfer chops to a serving platter; keep warm.
Add onion to skillet; cook over medium heat 2 minutes, stirring often. Reduce heat; add jelly and mustard, and simmer 2 minutes or until glaze is reduced to 1/4 cup. To serve, spoon glaze over chops.