MY BARGAIN wine discovery of the year so far is a wine from Alsace: a Riesling Rebgarten 2009, from the Pfaffenheim Co-operative. It is comparatively rare for a wine from Alsace to be sold with a vineyard name, unless it has the superior rating of a grand cru.

I showed this at a tasting for wine-trade students, and they all gave it a minimum retail price of £15. This is scarcely surprising, as 2009 is an outstanding vintage in Alsace. Perhaps I should warn you that this wine has the rather different smell and taste that is peculiar to many older Rieslings - that of mineral oil. Notwithstanding this, it is a wine that I, and the others, really enjoyed. The price? Just £6.99, at Lidl.

Those with a wine-drinking history of a certain length will remember when the British white-wine market was dominated by so-called Rieslings from Eastern Europe. In fact, these were not true Rieslings at all. The true Riesling is one of the great grape-varieties in the wine world, capable of producing not only outstanding dry wines, but also some of the finest sweet ones. It shows at its best in Alsace and Germany, but also in some of the cooler wine regions in Australia.

In Alsace, its pinnacle is widely considered to be from the small vineyard of Clos Sainte Hune, which belongs to the Trimbach family. Their other outstanding Riesling is their Cuvée Frédéric Emile. If you want to start at the top, Waitrose has the 2006 vintage for £33.99. A humbler representative, the Riesling Kaefferkopf 2012 Henri Erhart, is at Tanners, at £11.70. This has the classic minerality, as well as a crisp citric acidity.

From Germany, there is nothing I enjoy more than a chilled Mosel. Low in alcohol, often no more than eight degrees, and with a touch of sweetness, they are wines for social drinking. Such a wine is the Grey Slate Dr. L Private Reserve 2013 (Waitrose, £9.99) with complex flavours of apple and nectarines. If you prefer something sweeter, try the Wehlener Sonnenuhr Riesling Auslese 2011, Heribert Kerpen, a Dolly Parton wine with opulent rich fruit and no more than 7.5 degrees (Tanners, £16.90).

In other parts of Germany, the sweeter styles of Riesling have largely been abandoned in favour of dry wines with a distinctly higher degree of alcohol, such as Kendermann's Special Edition Riesling 2013, from the Pfalz region (12 degrees, Waitrose £7.49).

In Australia, the best Rieslings come from the Clare and Eden Valleys in south Australia, although wines from the south-west corner of western Australia and Tasmania are beginning to create a stir.

From the Clare Valley, I would suggest Jim Barry's The Lodge Hill 2013 (Majestic and Co-op, around £14); from the Eden Valley, Pewsey Vale The Contours Museum Reserve 2009 (Oddbins £16.99); and, from Tasmania, the Tamar Ridge Kayena Vineyard 2010 (Wine in Cornwall and Bowland Forest Vintners, £16.50). The Riesling revolution is well under way.