Sin quas originated in India but are now grown in many parts of the world. Luffa acutangula is named for its 10 strongly defined ridges that run the length of the fruit. Its common Chinese name, sin qua, means “silk gourd”, a reference to the gourds’ vascular system.
Sin qua vines are usually planted in spring and grown up and across a head-high trellis. The gourds hang below the foliage, making them easy to harvest. Sin quas are productive plants, with a single vine producing up to 25 large fruit. They grow best in a warm climate and are sometimes produced inside greenhouses.
Sin quas should be picked while still immature (15-40 cm long) to avoid them becoming fibrous and tough. They can be stored for a time but they easily lose water, becoming soft and spongy.
Good quality sin quas should be bright, glossy and firm. Sin quas have a slightly spongy texture and mild flavour somewhat similar to zucchinis. To prepare them, the hard ridges at least should be cut off with a potato peeler. The rest of the skin can be left on if the vegetable is young and tender.
Sin qua oxidises quite quickly so it can be useful to add a little lemon juice if it is not going to be cooked immediately. It can then be steamed, stir fried, grated into an omelette or fritter or added to soup.
Sin quas contain small amounts of calcium, phosphorus, iron and other micronutrients.