Freeze-dried food is shelf-stable, making it a top choice for emergency food supplies, military provisions and convenience products, such as instant coffee. Freeze-drying is literally a process of freezing an item -- it can be food, liquid, flowers or other organic substances -- and removing all of the liquid in a vacuum. You can add water to a freeze-dried food to return it to its previous form. Freeze-drying usually requires special machinery designed for commercial use, but you can freeze-dry thinly sliced foods in a home freezer.
Clear a space in the freezer large enough for the drying rack to sit flat.
Cut potato into paper-thin slices. A mandolin, a kitchen tool with a sharp blade that helps you cut vegetables quickly, can make very thin and even slices.
Lay potato slices in a single layer on the drying rack, and set it in the freezer.
Freeze potatoes for a full week. Do not cover them. You want the moisture from the potato to turn to frost on the outside of each slice, and eventually disappear, leaving dried-out, frozen pieces.
Cut a piece of potato from one of the slices and thaw it at room temperature. If it keeps its appearance and is hard when dry, it can be stored. If it becomes black, it is not fully dried and the slices need more time in the freezer.
Place freeze-dried potato slices in a bowl and cover with boiling water to reconstitute before using.
Use freeze-dried potatoes to make mashed potatoes.
Freeze-dry larger quantities or larger pieces of food, liquids and flowers in a commercial machine.