Place all marinade ingredients in a plastic ziplock bag with pork chops, seal and toss to full cover with marinade.
Refrigerate pork chops overnight.
Heat Port wine and plums in a small but deep sauce pan on medium high heat for 10 mins.
Mash plums and then strain mixture, return strained liquid to saucepan and continue to cook down until sauce has reduced to ½ cup and has thickened slightly.
Leave on low heat while grilling pork chops.
Heat grill and cook pork chops until internal temperature has reached 145ᵒ F and chops are lightly browned.
Pour reduction sauce over pork chops and serve with extra slices of plums if desired.