Green peppercorns are really unripe black peppercorns. These are often preserved in brine or vinegar and served in pickled form. In dried form, they don't last very long and have to be used quickly. They have a fresher flavour than their black counterparts. Green Peppercorns in brine are most famously used in the sauce for Steak au Poivre. They are a delicious addition to the preparation of sausages and terrines. They make an aromatic addition to the liquid used for steaming mussels and are also excellent for use in vinaigrette.