'Foie gras' is the fattened livers of ducks or geese. In France foie gras is served in 2 ways. One is 'foie gras poele' (pan-fried). Place a slice of duck liver in a pan on slow heat to cook until golden on all sides, then garnish with fruit or jam. Toasts are usually an accompaniment. This is favoured by connoisseurs.
Then there is the terrine. The whole liver is de-veined and marinated with salt and pepper, Cognac and Port. Then it's left in the fridge over night. The marinated liver can be packed either in a terrine-cooker or wrapped tightly in cling films, then cooked slowly over a water bath. The resultant terrine is good for days and is served cold.
You can buy foie gras preserved in vacuum jars which can be kept for years. Pay attention to the labels. If you see 'foie entire' (whole liver) then it is made from whole livers. If the word 'morceaux' appears then the jar is made from pieces of broken livers compacted. There are also jars consist of a percentage of liver mixed with duck meat.
There is a protest trend against eating foie gras because of the alleged cruelty of forced-feeding. Go try this delicacy if you're curious before it is banned.
Added to cart