Place chops on cutting board and pound with the spiked side of mallet to approximately 1/2 inch thick; place in a zip lock plastic bag.
In a small bowl mix together, capers, caper juice, mustard, 1 tablespoon brown sugar and reserved pineapple juice; mix well. Pour marinade into zip lock bag and massage into pork chops; marinate in fridge for at least 1 hour, 4 hours is best.
Heat olive oil in a large fry pan; sauté onions on medium high heat, approximately 6 minutes; push to the side of the fry pan, reduce heat to medium. Drain chops well; add to the fry pan with the onions and brown, approximately 5 minutes on each side. Remove chops to platter and keep warm.
Add marinade to pan with onions; on medium high heat reduce to half; push to the side of the pan, return chops to the pan.
Cut the pineapple rings in half and place one half ring on top of each chop. Spoon reduced onion/marinade mix on top of pineapple slice; sprinkle with remaining brown sugar.
Continue to heat only until sugar has melted and pineapple is heated through, 3 or 4 minutes.