Place pork fillet into a small greased baking dish. Combine Leggo’s Tomato Paste with seeded mustard and spread over pork.
Overlap prosciutto slices over pork completely covering top and folding excess prosciutto under pork.
Bake in a preheated oven at 180°C for 30 minutes. Remove from baking dish and allow to rest for 10 minutes. Gently crush hot potatoes with a potato masher. Add to the baking tray with the sage leaves and cook for 10 minutes, while pork is resting.
Cut pork into slices and serve with smashed potatoes and crispy sage.