Pound chops to 1/4" thick and cut into several pieces. Sprinkle lightly with pepper.

Melt 2 Tbsp. margarine in a large skillet. Sauté sliced mushrooms over med-high heat for 2-3 min. Add the lemon juice and cook until the liquid is evaporated, 1-3 min. Remove the mushrooms from the skillet. Add the remaining 2 T. of margarine to the skillet.

Cook the pork chops, half at a time, over med-high heat for 1-2 min. on each side. Add more margarine, if necessary. Remove the pork from the skillet and keep warm.

Combine the whipping cream and mustard. Return the mushrooms to the skillet and add the cream and mustard mixture. Stir over med-high heat until the sauce bubbles and thickens slightly. Pour the sauce over the pork and serve.