Sprinkle the pork chops with pepper. Heat the olive oil in a large, deep, nonstick skillet over medium-high heat. Add the chops and cook, turning occasionally, until browned on both sides. Transfer to a plate.

Add the onions, chicken broth, garlic, mustard, and thyme to the skillet. Bring to a boil Reduce heat and simmer, covered, stirring occasionally, until the onions are very tender, about 10-15 minutes.

Sprinkle the onions with the cornstarch, and raise the heat back up. Cook, stirring constantly, for about 1 minute, or until the sauce is bubbly and thickened. Return the chops and juices to the skillet. Reduce the heat and simmer, uncovered, until the chops are heated through, turning occasionally, 2-3 minutes.