Lay Pork slices on a cutting board. Using a meat mallet or the flat side of a heavy knife, pound each slice to an even 1/8-inch thickness. Sprinkle both sides of Pork with coriander, lightly pressing into meat. In a large skillet, heat half the oil over high heat. Add some Pork slices to skillet; cook in batches until browned, about 2 minutes per side. Place Pork on a plate. Repeat with remaining Pork slices. Add remaining oil to skillet and heat over medium heat. Add Onion and saute until soft, about 5 minutes.