When you prepare sweet potatoes like this, you get the best of both worlds: tender, buttery rounds of sweet potato with crisped, browned edges. To balance the natural sweetness of the potatoes, we toss the slices with vinegar, spices and red pepper flakes, then tuck sliced shallot and sage or rosemary leaves in between the layers. Sweet potatoes can vary greatly in size. Try to choose medium-sized ones of about the same diameter so the slices fit neatly in the pie plate. The quickest way to slice the potatoes is with a mandoline—aim for slices about ⅛-inch thick. Serve this with a pork roast or pork chops, or alongside the roasted turkey on the Thanksgiving table.