Trim pork tenderloin and season with salt and pepper. Wrap it with cling film and roll it like salami. Leave in the fridge for 10min.
Heat oil in a skillet over medium-high. Slice the pork fillet as it's wrapt in 3.5cm thick slices. Gently fry the medallions on each side for 2 min. Put them aside and remove the cling film. Return to the skillet and continue cooking for another 2 min. Do not overcook them as they will become dry. Remove from heat; let stand a few minutes before serving. Garnish as you like.