Drain 6 pineapple slices and reserve 1/4 cup pineapple syrup. In 9x13 inch metal baking dish, combine pineapple liquid with soy sauce, salad oil, minced onion, garlic and brown sugar. Place steaks in marinade; cover and refrigerate at least 3 hours, turning once.
About 40 minutes before serving, prepare grill or preheat broiler. Arrange steaks on grill or in broiler pan. Grill 15 minutes, brushing with marinade once.
Meanwhile, place pineapple slices in pan of marinade, turning to coat both sides. Place pan on grill while steaks are cooking to heat pineapple slices. If in broiler, heat pineapple on top of steaks during last 3-4 minutes.
Turn steaks and grill 15 minutes more, spooning remaining marinade over steaks once, until meat is thoroughly cooked and fork-tender. Serve a hot pineapple slice with each pork steak.