Alsace Riesling is on the increase here, but is choosy about where it is planted, preferring the hilliest, most sheltered sites. This might seem curious, given that Alsace is so much further south than much of Germany; but many of Alsace’s vineyards are on the flat plains rather than on the steep, church-dotted hills beloved of photographers of the region. Soils on the plains are richer and more fertile, and while they should not be dismissed out of hand – good viticultural practice can produce expressive wines here – Riesling in less skilful hands can be thin and anaemic, or heavy and flat.

On the best hillside sites, particularly in the hillier Haut-Rhin in the south of Alsace, Riesling comes into its own. (There are 50 Grand Cru sites in Alsace; their names are a fair guide to the best sites, but not all the best wines are Grand Cru, and not all Grand Cru wines are worthy of the name.) The soils Riesling likes best here are sandy-clayey loams that warm up quickly in spring, although it is less fussy about soil than it is about aspect; key vineyards include Brand, Clos Ste-Hune, Elsbourg, Hengst, Kaefferkopf, Kastelberg, Kirchberg (Ribeauvillé), Kitterlé, Osterberg, Rangen, Schneckelsbourg, Schoenenbourg, Sporen and Zahnacker.

But the geology of Alsace is so convoluted that soil types often change within the same vineyard: hence the habit of some top Alsace growers of picking such parcels separately and vinifying them as separate cuvées. Such cuvées may be blended later out of commercial necessity, but tasting them from barrel shows that Riesling in Alsace reflects its terroir just as clearly as it does across the Rhine in Germany – as long as the yields are not too high.

Permitted yields in Alsace are overgenerous: 100hl/ha for the basic AC wine and 55hl/ha for Grand Cru. Wines cropped at that level have little character and no concentration; serious growers quote around 50hl/ha for AC wine and less for Grand Cru.

Why does Alsace Riesling taste so different from German Riesling – different even from the Rieslings of the Pfalz, only just to the north? One reason is the soil: the predominantly calcareous, clayey soils of Alsace give a fuller character than does the slate of, say, the Middle Mosel. Another reason is their higher alcohol: Rieslings here commonly have over 12.5 per cent alcohol, and may be chaptalized.

They often spend longer in old barrels, too, which gives them greater roundness. But above all they are French wines, with the indefinable but recognizable French imprint. They are ‘winier’ wines than German Rieslings, lean and austere in youth but rich, honeyed and even petrolly in maturity.

They are also generally dry, although Alsace growers are notoriously cavalier about residual sugar levels. It is impossible to predict from a label whether an Alsace wine will be bone dry or medium. Vendange Tardive, or late harvest, wines may be dry or semi-sweet: Rieslings in this category must attain 95° Oechsle (220g/l sugar at picking). The much rarer Sélection de Grains Nobles wines are always sweet, and must have reached 110° Oechsle (256g/l sugar) at harvest.

Riesling is on a roll in Australia, although, since it only occupies a tiny percentage of total plantings, its current popularity may never amount to more than a mini-roll. Until Chardonnay overtook it in the early 1990s, Riesling was the most planted white grape in Australia, reflecting the belief current among many growers at the time that if you took a noble grape variety you could plant it anywhere regardless of climate or site and get great wine. It was (and still is) grown in many regions that were (and are) far too hot for such an early ripener; the resulting wines gave the variety a bad name.

Australia’s best known Riesling region, the Clare Valley, has enjoyed substantial growth since the early 1990s but Cabernet Sauvignon, Merlot and Shiraz between them have more than doubled over the same period. Investors in Clare, as elsewhere in Australia, are hypnotized by reds.

Clare is, on the face of it, a region far better suited to reds. Its climate is almost Mediterranean, but its topography makes it more adaptable than it would seem. Far from being a single valley, Clare is a series of gulleys, with hills rising to over 400m (1320ft) to the east and west. This already gives significant variations in temperature. In addition, nights are cool and rainfall is low, and the free-draining soils – which include red soil over limestone and shaley slate – allow for great variations of wine style. Watervale is traditionally the finest part of Clare for Riesling, though the Polish Hill River only a few miles north gives quite different wines with finesse and a certain mineral character. Clare’s stylistic affinities are with Alsace.

The great 1970s Rieslings from Leo Buring set a standard in Australia which is still inspiring winemakers three decades later. Such wines are lean, even apparently rather simple in youth: many are drunk in their youth because their crispness and freshness are attractive then and seem to promise nothing more. But with time the acidity softens, the palate deepens, and they develop flavours of buttered toast and lime and a melting honey richness – and sometimes a whiff of kerosene; they emerge into maturity as some of the richest, most complex dry white wines in the world. And all without a hint of new oak.