Instructions

1. Wear gloves or accept stained hands for two days. Beet juice binds to skin and soaks into a wooden board, so this is a job for a plastic one.
2. Peel the beets and slice them on a mandolin if you have one. A knife cut varies by a millimetre or two without your noticing, and on a root this dense that difference is the gap between a chip and a bendy disc.
3. Cover the slices with the water, vinegar and oil and leave them a quarter of an hour. The vinegar holds the color, which otherwise browns in the heat, and the oil carries it onto every face of the slice.
4. Lift the slices out and let them drain rather than tipping the bowl onto the trays. Liquid pooling under a slice takes as long to dry as the beet does.
5. Lay them out with no overlaps, then scatter the salt flakes on while the surfaces are still wet. Salt added after drying just falls into the bottom of the jar.
6. Dry at 135 °F for 8 hours. These shrink to roughly a third of their size, so expect the trays to look half empty by the end of the run.
7. Test one that has been off the machine for five minutes: it should snap cleanly and taste sweet rather than earthy. A chip that folds has water at its centre and needs longer.
8. Seal them in a jar the moment they are cold and use them within two months. The oil is what limits these — plain dried beet keeps far longer, and also tastes of much less.