- Spray a 10-inch skillet with the cooking spray and heat over medium heat for 1 minute. Add the mushrooms and onion and cook until they're tender. Remove the vegetables from the skillet. Remove the skillet from the heat.
- Spray the skillet with the cooking spray and heat over medium-high heat for 1 minute. Add the beef and cook until it's well browned, stirring often. Pour off any fat.
- Stir the soup, water, mustard and vegetables in the skillet and cook until the mixture is hot and bubbling. Toss the rice with the parsley, if desired. Serve the beef mixture with the rice.
Ingredient Note: To make slicing easier, freeze the beef for 1 hour.