Cut the pork fillet into medallions. Season generously on all sides with salt and pepper. Heat a large, deep non-stick pan over medium-high heat and fry the medallions 2-3 minutes per side until browned.
Mix the peach juice from one of the drained peach cans with the soy sauce and light ketchup. Pour this sauce over the meat, reduce heat to medium-low, cover with a lid, and simmer for 10 minutes.
Add the drained peaches to the pan, cover again, and simmer for another 10 minutes until the pork reaches 63°C (145°F) internal temperature.