Preheat the oven to 200C/400F/Gas 6.
For the saltimbocca, wrap two slices of parma ham around each pork medallion.
Heat the oil in an ovenproof pan and fry the pork for 1-2 minutes on each side, or until lightly browned.
Transfer to the oven and bake for 5-6 minutes, or until completely cooked through.
For the sautéed potatoes, heat the oil in a frying pan and sauté the onion and garlic until softened.
Add the potato and paprika and stir well. Cook until the potatoes are golden-brown and tender, then season, to taste, with salt and freshly ground black pepper.
For the leeks, heat the butter in a pan and sauté the leeks until softened.
Add the double cream and grated cheese and heat gently, stirring frequently, until the cheese has melted. Season, to taste, with salt and freshly ground black pepper.
To serve, place the saltimbocca onto a serving plate with the potatoes and leeks.