Preheat the grill to medium-high. Put the medallions between two sheets of greaseproof paper and use a rolling pin to bash the medallions to about 1cm thick.
Mix the parmesan and parsley in a bowl, and put the flour and egg in 2 separate bowls. Dip the pork in the flour, then the egg, and finish with the parmesan. Put on a baking tray and grill for 10 minutes, until cooked through – there's no need to turn.
Meanwhile, put the potatoes in a pan of cold water. Bring to the boil; simmer for 12 minutes. Drain and crush.
Combine the apple, carrot, mayonnaise, crème fraîche, mustard, and lemon juice and zest. Stir through the cabbage and rocket. Serve with the pork and potatoes.