Melt the butter in a pan, dust with the flour, stir and let brown lightly. Deglaze with port wine, pour in the stock and the juice from 2 oranges. Season to taste with pepper and salt. Add the ginger and let it simmer for 5 minutes until the sauce has a nice bond. Before serving, add the cream and a few drops of lime oil, bring to the boil briefly.
Goes perfectly with fish dishes (then use fish stock) and tagliatelle or poultry dishes (with poultry stock).
Tip: Orange oil also works great instead of lime oil.