Rhubarb

Botanically a vegetable, rhubarb is the culinary chemist's nightmare and dream. Its astringent violence stems from oxalic acid. Its thick fibers need to be peeled, then subjected to osmotic extraction (maceration in sugar) to draw out cellular water and soften its acidity. Heated, its structure collapses very quickly into a compote. To keep its shape in neat batons, low-temperature sous-vide poaching (65°C) in a light syrup is the only scientifically viable method.