This time around in our series on Basque terroir, I’d like to thank María José Cortés Lamas for her article, “What Makes the Basque Violet Onion so Awesome?” which serves as the inspiration behind this latest post. I was aware of the fact that Zalla, a town in the Enkarterri/Encartaciones region of Bizkaia some fifteen miles west of Bilbao, is a producer of Bizkaiko txakolina wine, but I knew nothing of its renowned red onions.
Onions, of course, are one of the most ubiquitous vegetables in the world, coming in all sizes, shapes, and colors. The onion is most frequently a biennial or a perennial plant, but is usually treated as an annual and harvested in its first growing season. Red onions in particular are high in flavonoids.
The red (or purple or violet, depending on your point of view) onions of Zalla are especially mild and sweet. As noted in the abovementioned article, for star Basque chef Eneko Atxa, of Azurmendi restaurant fame, they can be the key element to producing the classic red Bizkaian sauce (bizkaitar saltsa/salsa vizcaína). And, of course, as is only right and fitting, the Enkarterri Fest food festival, held each fall, gives pride of place to the red onions of Zalla.
A quick note on Bizkaian sauce: According to Hasier Etxeberria, author of On Basque Cooking (free to download here), “This particular kind of sauce is equally suitable for meat or fish. In ancient times, this was our most exported recipe: the vizcaína or Bizkaian.” He goes on to discuss this sauce and offers a detailed recipe (pp. 63-65).