Cut pork tenderloin into 1 in. thick (3 cm) medallions, season with salt and pepper and dredge in flour on both sides, shaking the excess.
Melt butter with 1 tablespoon olive oil in a pan or skillet over medium heat. Add pork medallions (do this in batches) to pan or skillet and sear on both sides, until golden. Each batch will take approximately 5 minutes. If necessary add more olive oil after each batch. Transfer medallions to a plate and cover with aluminum foil to maintain heat. Add wine to skillet, scraping the brown bits from the bottom of the pan or skillet with a wooden spoon, bring to a boil and reduce wine by half. Stir in whipping cream, chicken stock and mustard, lower temperature and continue cooking over low heat until mixture thickens and has a sauce consistency. Add few drops of lemon juice and season to taste with salt and pepper.
Return pork medallions and any cooking juices to the skillet or pan and allow to warm up for a few minutes.
Transfer medallions to a serving dish and spoon sauce over.
Serve with rice, potato puree, potato gratin and asparagus.