All the way from South America, rather like Paddington Bear, comes my new favourite vegetable, Yacon, Smallanthus sonchifolius, distantly related to Jerusalem artichokes and carrying with it a host of intriguing culinary possibilities.
What is it?
Yacon tubers form underground beneath a robust, leafy plant, slightly reminiscent when dug of large baking potatoes, but that is where the similarity ends. Yacon, meaning ‘water root’ in the Inca language, has flesh that is juicy, slightly sweet and yielding, with a flavour reminiscent of pears, or melons, with a hint of celery. In fact in its home country, this beguiling tuber is used in fruit salads as well as vegetable dishes.
A most exciting feature of Yacon is the super sweet syrup that can be extracted from it, containing an indigestible sugar, inulin. In effect the delicious toffee-tasting syrup is virtually calorie free, does not raise blood sugar, and so both tubers and sweet syrup are suitable for diabetics. The inulin in yacon syrup also has great benefits for the bacteria in the gut where it is said to aid digestion and boost the immune system. These health benefits have lead to yacon becoming a major crop, especially in the US where most of the syrup extraction takes place.
Yacon is a tender perennial plant, therefore with a little TLC, once you have your first plant, it should be with you forever; in fact its cultivation and care are very much like dahlias, so if you grow dahlias, yacon will be a cinch! It is rarely troubled by any pests or diseases, easy and willing to grow, but does however need a long growing season, the tubers bulking up in the late autumn, to be dug in mild years just before Christmas, in advance of any penetrating ground frost.
To start off, either buy rooted cuttings in the spring or get a division from someone already growing yacon. I usually treat my stored crowns like dahlias, starting them off in the greenhouse until shoots appear. At that point I divide into individual plants and pot up, before growing them on for planting out in May in a sheltered sunny spot, when all danger of frost has passed.
Yacon does appreciate a rich, fertile growing medium with plenty of well rotted manure and compost, deeply incorporated into the soil. Cultivating the soil to a good depth before planting greatly helps the process of lifting the crop in the autumn, otherwise the main tubers can break off and stubbornly remain in the ground.
Once planted out, a lush and leafy plant will quickly develop to a height of up to 2 metres, with small orange yellow flowers in the late summer. If things are going to plan, the burgeoning tubers will start to raise the soil circling the crown of the plant around September / October time
Harvesting and Storing Yacon
Leaving harvesting as late as possible will give the most cropping potential. When the moment arrives, usually when the top growth has been blackened off by the first air frost, cut back the remaining stems to about 10 cm and dig up the crown consisting of the bulky storage tubers (the crop), plus small propagation roots, or ‘buds’ growing just under the surface. The crowns for next year’s plants are stored much like dahlias for the winter in a cool but frost-free place where they won’t dry out.
The big tubers, carefully snapped from the crown, are crunchy, sweet and refreshing immediately — after washing and peeling can be eaten just like a carrot — but they do have the potential to become sweeter if left out in the sun for a few days. Only undamaged tubers can be stored for several months in paper or hessian sacks, much like potatoes, in a frost-free garage or shed. Any damaged tubers should be used immediately or made into syrup.
Yacon in the Kitchen
Crunchy yacon is a delicious and different addition to savoury salads — try substituting the apple in Waldrof salad with diced yacon, or combine grated carrots, yacon ‘sticks’ and sliced celery with a grain mustard vinaigrette — in fact it absorbs dressings and sauces of all kinds very readily, making it a tasty vehicle for other flavours. In the Peruvian tradition of ‘salpicon’ (fruit salad), versatile yacon can also make a delightful fruit dessert when chopped and added to your choice of pineapple, melon, papaya or mango, dressed with fresh orange juice. If used raw, the flesh of yacon will discolour, much like an apple, so after peeling and preparing, sprinkle immediately with a little dilute lemon juice, or dressing, to preserve its attractive white colour. Alternatively, for a hot dish, yacon can be roasted with other root vegetables tossed with olive oil, balsamic vinegar and herbs, or even just simply steamed.
Once you have grown enough yacon to have some spare you can think about extracting the sweet liquid using a food processor — about 12 kgs makes a litre of the precious syrup. Simply wash and peel the tubers in batches then whizz them up thoroughly; place in a large pan and simmer down gently at about 103 C until a delicious dark brown syrup is formed. This sweet liquid is wonderful on porridge, or has a great affinity with cocoa when making ‘guilt-free’ chocolate treats!