We foreigners are a fickle lot. When we find that French wines have become too expensive, we turn to the wines of Spain and Portugal. Then, when we've become mentally and financially adjusted to inflation, we jilt the Iberians and return to the French.

We credit Spain for sherries but demote its table wines to sangria. Ports are acclaimed, but the Portuguese table wines are judged by Mateus and Lancers. Not that there's anything wrong with the Pink Pair, but as one Lisbon businessman said, "We consider them to be children's wines."

In Washington we hare having one of our periodic flirtations with Iberia. This time the relationship should last. The Iberians are among the most affordable drinkable wines and, furthermore, our current interest coincides with changes in Spain and Portugal. Urbanization and improved standards of living there have led to a demand for better quality wines and, particularly in Spain, the wine industry has responded by shaking off centuries of tradition.

The Spanish government introduced a denominacion de origen system in 1970 and there are now more than 20 consejos, or regional committees, although modernization has not been uniformly welcomed and progress in some regions is slow. The premier regions of Rioja and Penedes are the source of most of our Spanish wines. The Riojana have had their own vintners' association since Philip launched the Armada. The labels of members of their consejo carry a seal of authenticity that looks somewhat like a trading stamp. The past decade has seen heavy investment in the rejuvenation of Rioja: new bodegas, new plantings and winery equipment for long-established bodegas and aggressive marketing. Top vintners have scrapped the excessively long aging in wood that robbed the smooth, mellow reds of their fruit and flavor. They are marketing crisper, fresher whites more suited to foreign palates than were the rather nutty, low-acid whites they used to produce. As a result Rioja is winning international recognition. From Rioja, where big is a sign of both quality and quantity, these bodegas export regularly to Washington: M. de Caceres, M. de Riscal, Paternina (a selection of reservas and fran reservas has recently arrived), Domecq Domain, Olarra, Bergberana, Cune and M. de Murrieta.

Penedes, near Barcelona, is dominated by the excellent champagne method, sparkling wines of Codorniu and Freixenet, and the still wines of Torres. A family firm, Torres has pioneered the blending of French and German grape varieties and traditional Spanish varieties, with remarkably good results. More than most Spanish producers, Torres understands the wisdom of supplying the world market with light, fragrant whites.

Regrettably the selection of Portuguese wines at local dealers is not as interesting as it could be; trade and shipping problems seem to be most of the cause. Although the Portuguese do have an appellation system, denominacao de origem, in which six regions have been demarcated, many good wines come from nondemarcated areas.Here is a sprinkling of those available from both side of the fence:

Vinhos verdes: the young, hence "green," crisp wines from the Minho. Greatly to be appreciated on a hot summer's day!

Dao: smooth, earthy reds. The fuller-bodied resrvas should be in better supply in the near future.

Bucellas and Colares: hard to find outside the Lisbon area. Our examples are not the most exciting.

Nondemarcated: the garrafeiras, or special reserves, of Carvalho, Ribeiro & Ferreira, Caves Velhas and Ribalta, and J. M. da Fonseca's Periquita are all good buys in reds.