Orange Sugar Cubes

A two-line method that depends entirely on one thing: the oil in the outer skin of the orange. Everything below is about getting that oil and keeping it.

• Loaf sugarIn this period loaf sugar meant hard sugar broken or nipped from a cone, sold in irregular lumps. Modern pressed sugar cubes work, but rough-cut Demerara or raw-sugar lumps have more open surface and pick up more oil.
• Rub the zest onlyPress the cube against the orange and drag it over the skin until the surface is coloured and damp. Stop when you reach white pith, which adds bitterness and moisture without fragrance.
• Choose the fruit for its skinSupermarket oranges are usually waxed and may be sprayed; the wax blocks the oil and takes the coating with it. Look for unwaxed or organic fruit, and scrub and dry it well before starting.
• Keep it dry and closedA damp cube will slump and cake. Let the finished lumps sit uncovered for an hour to dry, then seal them in a small jar with as little air space as possible.
• Use them within a monthUse them while fresh -- Citrus oil oxidises and the scent fades, so these are likely at their best in the first week or two. Better to make small batches than to fill a large jar.
• Yield and servingOne large orange will flavour roughly a dozen cubes. Reckon one cube per cup of tea; two or three will scent a jug of iced tea or a fruit punch.