Garlic Potato Purée with Shiitake Ragoût and Potato Crisps

Brush a baking sheet well with some of the oil. In a food processor fitted with the 2-millimeter slicing disk or with a hand-held slicing device slice thin the potato on the diagonal (cut one end of the potato on the diagonal to facilitate this) and arrange the slices immediately in one layer on the sheet. Brush the slices with the remaining oil, sprinkle them with salt to taste, and bake them in the middle of a preheated 400 °F. oven for 12 to 15 minutes, or until they are golden brown. Transfer the crisps while they are still warm with a metal spatula to a rack and let them cool. The crisps may be made several days in advance and kept in a plastic bag at room temperature.