Cheat Sheet: Kumquats

These small, attractive citrus fruit, their English name loaned from the Cantonese kam kwat, or golden tangerine, are now in season.

Types and shapes: Species and cultivars range in shape from perfectly round (above) to oval (below) and slightly oblong to pear-shaped. Round kumquats may be referred to as Marumi and oval ones as Nagami, after established Japanese exemplars. A third type, Meiwa, is a cross between the two.

Nagamis are the most intense-tasting and Meiwas are often the sweetest. All kumquats (kinkan in Japanese) have sweet rinds enclosing sour innards, with more membrane than pulp, and can be eaten whole, bar their few seeds.

Candied kumquats: Many styles are made around the world. At shops selling Vietnamese products, such as those at Golden Mile Complex, look for flower-shaped mut tac (right). Before being candied in thick syrup, these kumquats may be soaked in slaked lime (kapur) solution, which makes them firm, translucent and deep orange in hue. Also shown here are soft Taiwanese kumquats (left) candied with maltose and a hint of salt, which, like mut tac, can be added to baked items such as fruitcakes for bright bursts of colour and flavour. The small, pale, sweet-sour kumquats sold as ye shan lemons (right) by Chinese shops are best for snacking only.

Preserved kumquats: In the Chinese kitchen, kumquats are traditionally preserved in brine or salt. To do this, wash and dry kumquats, halve or slit them and pack them in a sterilised jar, interspersing them with generous sprinklings of sea salt. Cover and let sit at room temperature for at least two months. Shake the jar occasionally to redistribute the juices as they slowly seep out. Salted kumquats will keep indefinitely in the fridge. To use them, wipe off excess salt or juice then add to stews, soups or braises, as you would use salted plums, or steep in boiling water and sweeten to make a throat-soothing drink. Kumquats can also be made into marmalades, conserves and chutneys. They contain moderate amounts of pectin and hence should be mixed with other citrus fruits to obtain a more firmly set preserve.

Kumquat sauce: Taiwanese Hakka cooks make kumquat sauce for pantry use. Look for it at Taiwanese product fairs or make your own. Quarter and deseed tart kumquats, place in a pot with sliced fresh red chilli to taste, add water to barely cover and simmer until tender. Puree kumquats and chilli and season with sugar and salt as well as rice wine if desired. Bring puree to a boil and simmer for a couple of minutes, then cool and store in sterilised jars in the fridge. Use as a dip, dressing or condiment.

Hybrids: Producers have crossed kumquats with other citrus species to yield fruits such as limequats, mandarinquats and so on. None is farmed on an extensive scale, but may turn up occasionally in gourmet supermarkets here.

Calamondins: Kumquats are very often confused with calamondins, also known as calamansi limes, limau kasturi or "four-season tangerine" in Mandarin and Cantonese. While their precise origin is unknown, calamansi limes are thought to derive from a mandarin and kumquat cross and the aroma of their zest and juice does resemble both of these. Distinctly more sour than kumquats, calamansis contain more pulp and have tougher skins. They ripen to golden yellow (above) if plucked while green and turn orange if fully tree-ripened. The sweetened, preserved limes commonly sold in Singapore and Malaysia (right) may be mistaken for kumquats, but are calamansi limes.

Storing: Keep kumquats in the vegetable drawer in the fridge, loosely wrapped in a paper bag or swaddled in paper towels in a ventilated container. They spoil quickly if they get damp. Never eat kumquats from an ornamental tree unless you can confirm that they are edible and pesticide-free.

Text and photos: Chris Tan