Oleo Saccharum

Literally 'oil sugar' — a syrup made by macerating citrus peels in sugar.

Oleo saccharum is the historic base of the classic punch. Peel lemons or oranges thin, cover with sugar in a jar, let sit an hour or three; the sugar draws the essential oils out of the peel into a saturated fragrant syrup that no store-bought product can approximate.