Wrap 2 slices of prosciutto around each lamb fillet. Heat the oil in a large fry pan, cook lamb until cooked as desired. Cover, stand 5 Minutes, then slice into slices.
Meanwhile melt the butter in a pan, add onion, garlic and bacon, cook until onion softens.
Stir in wine, bring to the boil, reduce heat to a simmer, simmer a couple of minutes, stir in stock and peas, bring to a boil again until peas are soft, turn down heat, add cream, mix a little water with the cornflour add to sauce and stir until mixture thickens.
Blend or process mixture until smooth, stir in mint. Serve lamb with minted pea sauce.