Instructions

1. Sort the berries first and throw out anything soft, split or showing a fleck of mould. One mouldy berry in a punnet has already put spores on everything it was touching.
2. Freeze the berries overnight if you have the time. Ice crystals rupture the cell walls from the inside and do the same job as checking, with no boiling water involved.
3. Otherwise check them: sit them in a sieve, dip it in boiling water for half a minute, then plunge it straight into cold. The wax coat is waterproof, and an unchecked berry can sit on a tray all day and still be a wet ball.
4. Tip them onto a towel and roll them dry. Skins that go on wet stick to the mesh and tear open when you lift them off.
5. Space the berries so none are touching and dry at 135 °F for 13 hours. They roll about when the fan starts, so shake the tray once to settle them back into one layer.
6. Roll a handful between your palms towards the end of the run. Finished berries are hard, wrinkled and click against each other; any that squash and leave juice on your hand need longer.
7. Cool them on the tray, then condition them in a jar for a week, shaking it each morning. Blueberries come in a range of sizes and therefore dry at a range of speeds — the week is what averages the moisture out between them.
8. Once no mist forms on the glass, seal the jar and keep it dark, where they hold for a year. They will look duller than the day they came out; that is color loss rather than spoilage, and it is exactly why the cupboard should be dark.