Instructions

1. Choose spears that squeak against each other and have tight, closed tips. A tip beginning to open belongs to an old spear, and age means fibre, which drying only makes tougher.
2. Snap each spear rather than cutting the butt off. It breaks exactly where the woody part ends, and that is a different place on every spear and impossible to judge by eye.
3. Cut them into 7.6 cm to 10.2 cm lengths and keep thick and thin spears on separate trays. A fat spear and a pencil-thin one are two different drying jobs sharing one machine.
4. Blanch the pieces in boiling water for four minutes. This is not about cleanliness — it stops the enzymes that otherwise keep working inside a dried spear and turn it grassy and grey over a few months.
5. Drop them straight into cold water and leave them until they are genuinely cold, then drain and blot. Asparagus keeps cooking in its own heat, and an overcooked spear collapses on the tray.
6. Lay the pieces out without stacking, tips on their own tray where you can. Tips are delicate and finish well ahead of the stems, and pulling a whole tray is easier than picking through one.
7. Dehydrate at 60 °C for 5 hours, paying attention near the end. Asparagus scorches readily once the water is gone, and a scorched tip still tastes burnt in a soup weeks later.
8. It is done when a piece snaps clean and the tips crumble at a touch. Anything that bends is still holding water and goes back on.
9. Seal it in a jar in a dark cupboard for a year, and look at the glass after the first week. Fog on the inside means one piece was still damp and the whole jar needs another run.