Place a sheet of aluminum foil, shiny-side down, one edge toward you, on the work surface. Smear a small piece of butter in the center of the bottom half of the square. Arrange one quarter of the carrots, snow peas, and mushrooms in a mound on top of the butter. Arrange one quarter of the scallions, ginger, garlic, and sesame seeds on top. Sprinkle with a few drops of so