Heat the oil in a large pan, ten fry the beef on high for a few minutes until browned on all sides
Stir in shallots, peppercorns, bay leaf, and thyme. Cook for about 5 mins, stirring often until shallots turn golden brown
Pour in vinegar & let it bubble for a few mins until almost dry, now add wine & boil until almost completely reduced
Add the stock & bring to the boil again
Lower the heat & simmer gently for one hour, removing any scum from the surface of the sauce until you have the desired consistancy
Strain, check seasoning & set aside until ready to serve
Reheat in small saucepan over low heat