Melt the butter in a frying pan over a medium heat. Add the shallots and the ginger and fry for 2-3 minutes, until soft.
Add the port and boil until the liquid reduces to a very thick syrup, then add the stock.
Bring the stock to the boil, then add the redcurrant jelly and the green peppercorns and reduce the heat to simmer for 2-3 minutes, or until the jelly has completely dissolved.
Remove from the heat and serve.