Heat olive oil in a large skillet, over medium-high heat. Add pork slices and brown 2-3 minutes per side.
Remove meat and set aside on a plate.
To the same pan add onion and cook for 3 minutes, stirring constantly. Add mushrooms and cook for another 5 minutes, scraping the bottom and sides of the pan.
Add chicken broth, mustard, and heavy cream, and stir to combine.
Return pork to the pan and bring to a boil and let simmer for 2-3 minutes. Add salt and pepper to taste, if desired. Remove from heat and serve over rice.