Step 1Clean the foie gras by gently separating the lobes and removing any visible veins. Roll it back into a cylindrical shape and slice into eight pieces, each about three-fourths of an inch wide. Reserve in the refrigerator.
Step 2Tear the frisee into bite-sized pieces. Rinse and drain, discarding any discolored pieces. Set aside.
Step 3Slice the pears lengthwise into quarters. Remove the cores and cut each quarter into thin slices.
Step 4Heat a saute pan to medium high. Sear half the foie gras slices quickly, allowing the flesh to change color and the bottoms to turn brown, 45 seconds to 1 minute per side. Remove from the heat and reserve (do not drain). Pour the fat out of the pan and reserve. Repeat the process with remaining foie gras slices, but do not drain the fat.
Step 5Briefly saute the pear slices in the foie gras fat over medium heat, until the pears just begin to change color, about 2 minutes on each side. Remove from the pan and set aside.
Step 6Add the shallot to the pan. Cook over medium heat until tender, about 2 minutes. Pour the fat and shallot into a large bowl.
Step 7Reduce the heat to low. Add the vinegar and cook, scraping up the caramelized bits in the pan with a wooden spoon, until the liquid is reduced by half, about 1 minute. Pour the reduced vinegar into the bowl with the shallots and fat. Add a pinch of salt and pepper and 1 to 2 tablespoons of the reserved fat. Whisk to combine. Taste and adjust the salt, pepper and sugar to taste. Add the frisee to the dressing in the bowl and toss.
Step 8To assemble, divide the pear slices among eight salad plates. Top each with a small handful of dressed frisee and a piece of foie gras. Sprinkle with a pinch of salt. Serve warm.