Limau asam boi (lime with sour plum)
Order 'limau ais asam boi' at a kopitiam in Penang or a hawker centre in Kuala Lumpur at the hottest part of the afternoon and it arrives in a tall, sweating glass: freshly squeezed calamansi or small green limes, a little syrup, ice and one wrinkled, salted dried plum. The plum slowly leaches salt and fruity sourness into the drink, so every sip changes, starting bright and sweet and ending salty and tangy; you squash the plum with your straw halfway through for a stronger hit. It goes with char kway teow, nasi lemak or anything fried. The usual mistake is using bottled lime juice, which tastes flat and bitter against the plum. Squeeze fresh limes, and add the syrup gradually because asam boi is already salty-sweet. It is ready when the glass is frosted and the plum has started to plump up. Asam boi is sold in jars in Chinese and Southeast Asian groceries; Japanese umeboshi is saltier but works if you halve the amount. Chef's tip: make the lime-syrup base ahead and keep it cold, then pour over fresh ice only when you serve.
























