what can i do with leftover terrine of foie gras and how long will it stay good?
If the exposed parts of your terrine are turning greyish, cut off the grey (eat it -- it's okay, just discolored) and coat the rest of the terrine with melted butter or duck fat.
The only time we have filet mignon in our house (we prefer fattier cuts) is when I grill them quickly and top 'em with a slice of foie gras or liver pate. Pass the Madiera sauce.
Stuff chicken breasts with the terrine and maybe some mushroom duxelle, start in a saute pan and finish in the oven.
I had a really wild pasta dish in a restaurant that was fettucine in a cream sauce that was chock full of cubes of pate.