Instructions

1. Basil is a morning job. Once the sun is properly on the plant it has already burned off some of the oil you are trying to capture, so cut after the dew has gone and before the heat arrives.
2. Wash the leaves in cold water and lay them out on a tea towel until the surface is dry to the touch. Water still clinging to a leaf is work the machine has to finish before it can start on the basil.
3. Pull the leaves off the stalks and throw out anything blackened or bruised. A damaged basil leaf has already begun to oxidise, and it comes out of the machine black instead of green.
4. Heap the leaves onto a mesh insert in a loose layer about the depth of a fingernail, rather than laying them out one by one. The fan needs a path through the pile, so rock the tray until the heap sits level instead of flattening it with your palm — and a leaf light enough to lift onto the element is a burnt leaf.
5. Dry at 40 °C for 6 hours, pulling one leaf out halfway through to test. It is finished when it breaks into green flakes under light pressure and will not fold.
6. Leave the setting where it is rather than pushing it up to save an hour. Of every herb on this site basil is the one that browns first, and brown basil has lost exactly the sweetness that made it worth a tray.
7. Give the tray ten minutes on the bench before you touch anything. Basil straight out of a warm machine always feels further along than it is, and leaves jarred hot will fog the glass by evening.
8. Keep the leaves whole if you have the jar space. Whole leaf holds its oils far longer than crumbled does, and it takes a second to crush between finger and thumb over a pan. A full load comes back as roughly a twelfth of what went in.
9. Put the jar somewhere dark with the lid tight, and look at it again seven days later. Beads on the inside of the glass mean the batch was not finished, and the leaves belong back on a tray.