In a large heavy skillet, heat the oil. Flour the pork chops, and brown them on both sides in the oil, at medium-high heat. Remove pork chops from pan.
Add the onion rings to the pan and sauté briefly (about 1 minute). Return chops to pan and add pears and water. Cover pan and cook at low heat for 45 minutes.
Sprinkle marjoram over chops; cover pan and cook an additional 20 minutes, until chops are tender and sauce is thickened. Add grapefruit sections to pan, stirring and turning chops until sections are incorporated. Serve immediately.
