Place the flour in a shallow dish and season with salt and freshly ground black pepper. Place the eggs in another shallow dish. Place the panko crumbs, sage and parmigiano in a third shallow dish. Coat the schnitzels with flour, dip in the egg, then coat with crumb mixture. Allow to stand for 5 minutes. Cook the schnitzels one at time. In a large frying-pan, heat 1 tablespoon of oil until shimmering then add 1 tablespoon of butter. Just as the butter is melting, add a schnitzel and fry for 2 minutes on each side or until browned. Remove and keep warm while repeating with the remaining schnitzels. Just before serving, in a small frying-pan heat the remaining 4 tablespoons of olive oil until shimmering and fry the whole sage leaves for a few seconds until crisp. Serve the schnitzels with mashed potato and garnished with fried sage leaves and with lemon quarters alongside. SIMON SAYS: Freeze the rinds of hard cheese such as Parmigiano-Reggiano and use them to enrich the flavour of any soup. Toss them into the pot, simmer, and remove before serving.