Heat 1 Tbsp oil in a large non-stick skillet over medium-high heat. Add pork and cook 2-3 minutes per side until lightly browned and just barely pink in the center. Remove to plates; cover loosely with foil to keep warm.
Reduce heat to medium, add mushrooms to pan and cook, stirring occasionally, 5 minutes or until lightly browned and soft. Stir in 1 1/4 cups water and gravy mix. Cook 3 minutes or until thickened, stirring occasionally. Spoon over pork. Garnish with parsley, if desired.