Marinate the steak in bowl with pineapple juice for 25 minutes. After marinating, remove the steak from the juice and sprinkle 1 tablespoon of brown sugar on each side. Discard the pineapple juice.
Heat a large skillet on medium heat and melt the butter or margarine. Evenly sprinkle the remaining 1 tablespoon of brown sugar in the pan. Place the pineapple slices around the outside of the skillet, reserving one ring and leaving a space in the middle for the steak.
Place the steak in the middle of the skillet and place one ring of pineapple on top. Once the steak is browned on the bottom, turn over, cover the skillet with a lid, and cook on low for an additional ten minutes.
Serve the steak with the sauce from the pan and pineapple rings as garnish.