Lemon Sugar Cubes

A one-line method that depends entirely on the oils in the peel, so the choice of lemon and the dryness of the sugar matter more than anything else.

• Loaf sugarLoaf sugar was a hard cone or block, broken into lumps with sugar nippers — dense and abrasive, which is what makes the rubbing work. Modern pressed sugar cubes are the closest thing; they crumble faster, so press firmly but do not scrub.
• The hinge: rub only the coloured zestStop as soon as the cube turns yellow and stops taking colour. Once you reach the white pith you are grinding in bitterness, and the cube will taste of it for as long as it lasts.
• Choose an unwaxed lemonSupermarket citrus is usually waxed and often treated with fungicide, neither of which was on the fruit when this was written. Buy unwaxed or organic, or scrub in warm water and dry thoroughly — the recipe's "wash and wipe dry" is not a throwaway instruction.
• Dryness is everythingAny moisture left on the rind or the cubes will dissolve the sugar's surface and the lot will cement together in the jar. Let the finished cubes air-dry an hour on a plate before they go in.
• StorageAn airtight glass jar in a dry cupboard, not the fridge. The lemon oil fades within a few weeks, so make small batches rather than a season's worth.
• Yield and useOne lemon will flavour roughly a dozen cubes. One cube sweetens and scents a cup of tea, which is the use the recipe itself names; a few would serve for a jug of iced tea, soda water or lemonade.