It is fascinating when an off-piste style appears, spontaneous yet splendid. That’s the case with palo cortado sherry - and this is the time you should try it, as International Sherry Week approaches.

In a world where much wine production is tightly controlled and the results predictable, it is fascinating when an off-piste style appears, spontaneous yet splendid. That’s the case with palo cortado sherry - and this is the time you should try it, as International Sherry Week approaches.

Palo cortado, the rarest of sherries, is a fino which has, effectively, gone wrong. The important layer of yeast, known as flor, that develops naturally over the ageing wine dies off and the wine starts to oxidise.

Then, there’s some extra fortification, taking the finished wine closer to 18-20 per cent alcohol than fino’s 15 or 16. This is largely the process, too, which creates amontillado (proper dry amontillado, not the bastardised over-sweetened style which now must be labelled “medium sherry”), but here the flor is usually present for longer and its death owes more to the winemaker’s intervention than to fate.

Next stage up in the dry sherry hierarchy is oloroso, which is aged oxidatively, ie without flor, from the beginning.

In scent and flavour palo cortado falls somewhere between that and amontillado.

By the very nature of their existence, palo cortados are individual, but that’s part of the very particular pleasure they give. Their delicate and intense aromas, complex flavours, nutty savouriness and overall refinement make them both great aperitifs and good food wines - think cured meats or soft blue cheese, perhaps, as well as nuts and olives.

And that conveniently leads to a crucial sherry characteristic: it’s one of the few wines where there are styles to go with all courses of a meal, from a sushi starter (salty-tanged manzanilla) to chocolate puddings (pedro ximenez, a dessert in itself when poured over good vanilla ice cream).

However you drink it, good sherry is special.

“There’s the whole story behind it, all the love and care that goes into it,” says Sue Daniels, responsible for the excellent line-up at M&S - the Gold Medal Sherry Selection case of six half-bottles (£48, marksandspencer.com, individual half-bottles £8 in most stores) has Very Rare Old Dry Amontillado, Palo Cortado and Oloroso from top producer Lustau, all superb wines and an intriguing comparison.

Most supermarkets source their serious sherries from respected names, and they are one of the biggest wine bargains - for example, the excellent Waitrose Solera Jerezana Palo Cortado, also from Lustau, is a penny under £10 for a full bottle. Independents, too, have great selections, keenly priced.

Slowly, sales of proper sherry are increasing here, thanks partly to the popularity of tapas.

International Sherry Week, November 7-13, aims to boost them more. Watch sherry.wine/sherryweek for details of London events.

Organic and biodynamic wines

The theme linking these recommendations is that they all come from growers who follow organic/biodynamic practices, a commitment showing in pure, expressive results.

Mas de Romanin Alpilles Blanc 2014 (£8.95, thewinesociety.com) brings back summer.

From Provence, vermentino with a touch of roussanne, it is aromatic, fresh and full of interest. Great value.

Forget about “old” mass-market German riesling, those dilute, boring, oversweet wines.

Jacobus Riesling Trocken 2015 from top grower Peter Jakon Kühn (is elegantly dry yet full of apricot and citrus flavours - a delight.

Kühn’s Oestrich Lenchen Riesling Kabinett is a splendidly harmonious off-dry alternative (£12.70 and £13.90 respectively, tanners-wines.co.uk).

Faugères is a small and beautiful example of the best of Languedoc - read all about it in Rosemary George’s excellent new book The Wines of Faugères (Infinite Ideas).

For proof, drink Le Portail 2014 from Domaine des Trinités (£12.50, leaandsandeman.co.uk), happily combining syrah savouriness with herb-drenched grenache and mourvèdre fruit.