Remove white skin from meat and cut into 1/2” thick medallions and tenderize. Salt and pepper to taste.
Heat oil in large skillet over high heat. Add prepared meat and saute’ for 5 minutes. Remove from pan and keep on a warmed plate.
Place mushrooms and onion into the skillet and cook about 3-4 minutes.
Add cream and let cook for 5-7 minutes.
Add tomatoes, mustard and butter. Salt and pepper to taste. Serve over rice pilaf.