Foie Gras : Separate the two lobes. Keep the smaller one for a later usage, such as a terrine. Make 4 slices of about 90g from the larger lobe and keep chilled.
Aïgo boulido : Clean and slice vegetables. In a saucepan filled with water, boil vegetables, spices and butter for 20 minutes. Strain and put aside.
The robustness and origins of the different herbs may require proportion adjustments. Quickly blanch all the herbs in salted, boiling water. In a food-processor or blender, add the herbs and slowly add the aïgo boulido while mixing. Strain. Add salt. Let cool and add a few drops of rendered foie gras fat. Correct the fluidity if necessary.
Just before serving
In a frying pan, cook the liver pieces, removing fat from the pan while cooking. Using the finest needle possible, probe the foie gras to check doneness. To do this, leave the needle in for about 10 seconds at the edge of the upper lip (the most sensitive spot). The needle should be warm. In the center of each plate, pour a little of the jus of fines herbes and drop flecks of foie gras fat. On the foie, place a bouquet of the aromatic herbs that make up the jus, and season with a few grains of fleur de sel.