Melt 2 tablespoons of unsalted butter in a large nonstick skillet over medium heat. Add shallots, and cook, stirring occasionally, until clear and translucent, about 2 to 3 minutes. Add mushrooms and thyme; saute until fork tender, 5 to 7 minutes. Season to taste with salt and pepper.
Heat oven to 500 degrees. Slice potatoes very thin, preferably using a mandoline. Brush a baking sheet with clarified butter, and arrange potato slices in a single layer. Brush the top of each potato with remaining clarified butter. Season with salt and pepper. Bake in oven, 5 to 7 minutes. (Leave the oven on for the packages.)
While potatoes cook, prepare leeks. In a large nonstick skillet over low heat, melt remaining 2 tablespoons unsalted butter. Add leeks, orange zest, ground coriander, and mirin. Cook, stirring occasionally, until leeks are tender, clear, and translucent, 5 to 7 minutes.
Fold four 10-by-16-inch rectangles of parchment in half, bringing the shorter ends together. Then cut the shape of half a heart, starting at the bottom of the fold, as if you were making a valentine. Unfold the hearts. (Each should be about 10 inches long and 8 inches wide at its widest point.)
Assemble each package by arranging a bed of 6 to 8 potato slices on one half of the parchment heart; then add layers of 1/4 cup leeks, 1/4 cup chanterelles, 1/2 cup raw bay scallops, and a dollop of truffle butter.
Fold the other half of the heart over the food. Seal the package by folding the two edges of the heart together; allow enough room for steam to accumulate. Place the packages on an ungreased baking sheet, and bake until the paper puffs and the contents bubble, 4 to 5 minutes.
Place package on a plate, and cut open just before serving. Accompany each with a small bowl of apricot mignonette for dipping.