Sorrels

Sorrel is a perennial vegetable that takes me back to my childhood. Roaming the hills above our house, thirsty from having forgotten to take water, I would seek out the apple-green leaves of Rumex acetosa. They did nothing to really stop me getting dehydrated I’m sure, but the rush of saliva brought on by the acid taste always made me feel better. We called them souries (pronounced soor-eez) from the sour taste, but the more widespread name is common sorrel.

Sorrel is a taste-name rather than a strictly botanical one: the various plants that are called sorrel are not all related but do all share that same sharpness, produced by the oxalic acid in the leaves. The oxalic acid means that it isn’t wise to eat sorrel in large quantities as it binds up calcium and can cause deficiencies, as well as contributing to diseases like gout. In small quantities however it is fine and in fact there is a small amount of oxalic acid in many accepted food plants including spinach and rhubarb.

Common sorrel

Several of the sorrels are in the Rumex genus. Sheep’s sorrel, R. acetosella, is tasty but probably too small to be worth cultivating deliberately. Buckler-leaved sorrel, R. scutatus, is also small-leaved but very productive and the leaves with their cool shape look great in a salad. My old friend common sorrel, R. acetosa, is the one that gardeners have paid most attention to and there are many cultivated forms, bred for larger leaves, mostly going by names like French sorrel and Polish sorrel. There is also a non-seeding form called ‘Profusion’ which is available from Poyntzfield Herb Nursery – ideal as it puts all its energy into producing leaves.

Buckler-leaved sorrel

Other sorrel-tasting plants are in the genus of Oxalis. I don’t know whether Linnaeus named the genus after the acid or whether it is the other way around. Oxalis is a huge genus with around 800 species, variously known as sorrels (which they aren’t), shamrocks (which they aren’t) and grasses (which they aren’t). Confused? You will be with common names.

As an aside, the genus includes Oxalis tuberosa or oca, an important root crop in the Andes which could also be grown here if only they could find a day-neutral variety. As it is, it only starts to form tubers when the day length drops below a certain critical number of hours, fine for the Andes but not much use in a climate where the first frosts might well be in September. I grew it productively for several years until an early frost wiped out the lot. All is not lost, however: it was the same story with the original potato until a mutation made it day-neutral and allowed it to conquer the world.

The only Oxalis I have in my forest garden is O. acetosella, the native wood sorrel. It is not very productive so it is more of a curiosity than an important part of my diet. As well as being eaten the leaves can be dried and used to make a tea. There is even apparently a sorrel tree, Oxydendrum arboreum, which is a member of the heath family, but a whole tree of sorrel might be too much of a good thing.

I mostly use sorrel chopped into a salad, but its most traditional use is in sorrel soup, particularly in Eastern Europe, where it is sometimes known as green borscht. Here’s my favourite sorrel soup recipe.

Ingredients
oil
1 onion, 1 clove garlic, chopped
1 potato, cut up small
600 ml stock (1 pint)
1 handful sorrel leaves, chopped
optional: 1 egg, beaten

Fry the onion in the oil until soft, then add the garlic and the potato and fry for a couple minutes more before adding the stock. The stock can be whatever kind you like: chicken is traditional but I use vegetable. Bring to the boil and add the sorrel leaves, which will immediately lose their bright green colour and go much darker. Cook for around 10 minutes until the potatoes are soft, then blend and serve hot or cold.

The size of the handful of sorrel leaves depends on how sour you want it to be. One hundred grammes (4oz) or more will give give it a good bite; 50g (2 oz) will give a hint of sorrel that slowly grows on the back of your tongue as you work your way through a bowl, an effect that I quite enjoy.

For a twist, you can add a beaten egg at the end, cooking for a few more minutes, which gives the soup a lot of body. Serve with a hard-boiled egg or a dollop of sour cream (the mallow flower isn’t strictly necessary, but there were lots of them growing next to the sorrel patch).

Growing and eating garlic mustard

Garlic mustard (Alliaria petiolata) is a phenomenally successful plant. In its native range it grows from Ireland to China and from Africa to Scandinavia. In North America, where it is introduced, it is frankly rather too successful. Unpalatable to native grazers and naturally vigorous, it has become a serious invasive pest. As well as taking up space, it produces chemicals which interfere with the native mycorrhizae and sets a nasty ecological trap for a native butterfly. The caterpillars of some species of garden white butterfly naturally feed on toothwort (Dentaria). Unfortunately, garlic mustard looks very like toothwort and the butterflies are suckered into laying their eggs on it. When the larvae hatch, they are unable to digest the garlic mustard and soon die.

In its native range, garlic mustard (a.k.a. hedge garlic, Jack by the hedge and sauce alone) is much better behaved and an excellent candidate for the forest garden. Every part of it is edible, including roots, leaves, flowers and young seed pods. Flavour-wise, it does what it says on the tin, tasting like a cross between garlic and mustard. The roots are the hottest part, with a horseradish-like bite.

Garlic mustard is quite early to come into leaf and the youngest leaves are the mildest, so it’s a useful winter/spring green. As the year goes on the leaves get hotter and a bit acrid. I use them in salads and as a pot herb and often stick a leaf or two into sandwiches. There are much more imaginative ways to use it than this however. The one upside of the garlic mustard invasion of North America is that people have put some serious effort into finding ways to cook them in an effort to eat the interloper into submission.

Pesto seems to be a favourite, with the oily ingredients acting to balance the mustardiness. One recipe combines the pesto with green lentils and one particularly adventurous one throws in the roots for good measure. Garlic mustard roulade wins my prize for the most beautiful recipe and one person has even pickled the roots which must taste amazing.

Garlic mustard is a biennial, growing lots of leaf in its first year then running to seed in its second. It is a very vigorous seeder, so unless you want to end up feeling like North America, I suggest that you pull up most of the plants in the second year and just leave a few to provide the next generation. Be prepared to treat it as a weed in the rest of the garden and hoe it out ruthlessly if it seeds beyond where you want it. It is shade tolerant, growing in either full or partial shade (under a Victoria plum in my case) and not fussy as to soil.