Place in a mortar half a tablespoonful of coriander seeds and four cloves; bruise them well, then put in a saucepan one and a half breakfast cupfuls of gravy, and one cupful of essence of ham, together with the thinly shredded peel of half a lemon, and the bruised seeds of the cloves; when it is boiling, add two bay leaves, two garlic cloves, and a head of celery sliced. Boil until reduced to half its quantity, and then add a wineglassful of white wine; strain through a fine hair-sieve, and work in well a tablespoonful of butter and a similar quantity of flour, and put all back in the saucepan, stirring the sauce over the fire until thick. It should be served while hot with roast fowl or meat.