For the foie gras butter: Combine the foie gras and 4 ounces of the butter in a food processor and puree. Transfer Foie Gras Butter to a small container, cover with plastic wrap and refrigerate.
For the wild mushrooms: Heat a large saute pan over a high heat (large enough to hold all the mushrooms in a single layer). Add 1 tablespoon olive oil and then the mushrooms. Cook over high heat until crispy around the edges -- approximately 3 to 5 minutes. Remove the mushrooms from the pan and let cool.
For the potato mousseline: Place potatoes in a saucepan, cover with cold water and bring to a boil over medium heat. Reduce the flame to low and simmer until very tender. Drain immediately and place in a food mill (not a food processor) or potato ricer. Rice or work through the food mill, adding 1/4 pound of butter, stirring constantly. Add 1 to 2 tablespoons of warm milk so that the puree is silky but not runny. Cover with plastic wrap and keep and keep warm over a double boiler.
For the gremolata: Combine chopped parsley, lemon zest and garlic.
Sear the scallops: Heat a saute pan over high heat. Season scallops with salt and pepper. Add 1 tablespoon oil to the pan. Sear the scallops until golden on one side, flip and then sear the other side. Remove from pan and keep warm.
For the truffle vinaigrette: Combine truffle juice, port and the juice from the truffle peelings in a non-reactive saucepan. Reduce over medium-low heat until reduced by about 3/4 or until liquid is a thin syrup. Remove from heat and cool.
Combine port - truffle reduction with vinegars and whisk in the oils. Set aside. This mixture will keep for 1 month in the refrigerator if it is tightly covered.
For the assembly: In the center of 4 large plates place a dollop of the potato mousseline. Reheat the mushrooms and sprinkle with gremolata to taste. Arrange mushrooms around the potatoes. Drizzle the foie gras butter over and around the mushrooms. Drizzle the truffle vinaigrette on and around the mushrooms. Place 3 scallops on top of each of the mounds of potato mousseline.