"Une poêle" (pronounced "pwal") is a frying pan, so we have the verb "poêler"(pronounced "pwale") which means to cook in the pan. So we use the word "poêlée" (pronounced "pwale") for anything cooked in a pan, with a more or less reasonable amount of fat, generally at a medium to high heat. In the case of your foie gras poêlé, it will be quickly seared on each face on a high heat.
Poêler is very similar to sauté, except that sauté is generally used for vegetables you will put in a small amount of fat on a high heat for a short time.
For professional chefs, when it comes to meat, "poêler" can also mean put in the oven in a "poêlon", which is a different kind of poêle that is thicker and can go to the oven. So very often they will start cooking the meat in the poêlon on the fire to sear it, and then finish the cooking process in the oven in the covered poêlon for a maximum tenderness and juiciness.
Sorry for the complicated explanation but with French cuisine nothing is simple...
Now for your sauce there are many possibilities for a foie gras poêlé : with white wine, red wine, balsamic vinegar, red wine and honey... But they would all start the same way: once you seared your foie gras put it on a plate, turn up your fire to a high heat, and add the liquid to deglaze (you can also add shallots first, but I woulnd't suggest garlic whose taste is too strong for the foie gras). If you're using wine or another alcohol, wait until all the alcohol has evaporated, otherwise it will give acidity to the sauce (you can't really see it but you can smell it!). Let us know how it went!