Heat oil in large skillet over medium-high heat. Season pork slices with salt and pepper. When oil is hot, add pieces of pork and sauté 2-3 minutes per side. Do this in batches so as not to overcrowd. Transfer pork to plate and keep warm.
Add fennel to skillet and sauté 1-2 minutes; stir in 1/4 cup water; cover and cook 4-5 minutes or until fennel is crisp-tender.
Stir in the Mustard and whipping cream. Heat over low heat for 4-5 minutes.
Return pork and any accumulated juices to skillet and cook 3-4 minutes or until hot. Garnish with chives, if desired.