I never had a recipe or been shown so I have just made it up myself with trial and error.
I take a large chunk of butter and melt it in a cast iron frying pan on a low heat and throw in a whole jar of chopped green pepper corns. Add slowly a 500ml container of cream, season with salt and ground black pepper and simmer on low heat until the mix thickens slightly and takes on a lightish green hue.

Should taste delicious esp poured over slices of medium rare eye fillet. Once I couldn't find the green peppercorns and so I made this sauce with ground black pepper and that's quite nice but lots more heat and off course more peppery.