Potato Latkes with Foie Gras & Apples

Notes: Most potato pancakes are too moist and depend on flour to absorb all the water, which affects the texture. This method endeavors to remove as much water as possible, so that little flour is necessary. Take the time to drain and press the shredded potatoes - you will see a difference in the lightness and flavor of the final product.

1. Add apple trimmings to demi-glace, bring to a boil, then simmer for 30 minutes. Strain and keep warm.
2. Meanwhile, place the apple slices in a nonstick saucepan with the butter. Cook for several minutes. Add orange juice and zest, lemon juice, Armagnac, and salt to taste, and continue cooking until apples are tender, about 20 minutes over low heat. Remove cooked apples from the pan, add the strained demi-glace to the pan and allow to cook for a few minutes to pick up the butter and apple flavor, then reduce until thickened.
3. Fill a bowl with cold water. Using a wire grater, grate 2½ potatoes into the bowl of water. Switch to a box grater, and use the largest holes to shred the last portion of the potato; this gives the potato pancakes texture. Add 1 tablespoon of salt to the water.
4. As with the potatoes, first use the wire grater to for the first half of the onion, grating it into the potato and water, then shred the other half into the bowl. Allow the potatoes and onions to soak for 15 minutes. Strain the water, and discard. Press the shredded potatoes in the strainer to remove all water, then toss them and press again. Note the white starch collected at the bottom of the bowl - do not discard it. Toss the potatoes in the sieve and press again. Pour off any remaining water.
5. Put the drained potato, which should be dry enough to stick together at this point, in the center of a clean kitchen towel. Fold the towel over the potato pile, then roll it and twist in opposite directions over the sink to squeeze out every possible drop of water.
6. Return shredded potato to the bowl with the starch, add the eggs and yolk to the mixture, add a teaspoon of salt and several grinds of pepper. Sprinkle baking power on the potatoes, and just enough flour to cover the surface. Stir gently to incorporate.
7. Heat enough duck fat to measure about ½ inch deep in a large heavy skillet.
8. Form the mixture loosely into pancakes roughly the size of a pack of cards. If too moist, add a little more flour and stir to incorporate. When fat is hot, about 375 degrees F, add only as many pancakes as will comfortably fit in the pan without crowding, flattening them slightly. Cook until browned and crispy on both sides, turning once - carefully as the duck fat is hot. Remove with a slotted spatula, blot on paper towels or a cooling rack, and keep in a warm oven as you make the next batch.
9. Allow duck fat to cool slightly, then pour duck fat through a fine strainer to remove any potato bits. Set the fat aside to re-use, and wipe out pan. Heat pan until very hot.
10. Season foie gras slices with salt and pepper, and sear until lightly browned and medium-rare inside, about 45 seconds per side.
11. On warm plates, place a potato pancake, then add an apple slice and a foie gras medallion on top. Spoon on sauce, and serve with applesauce and creme fraiche if using.