The third vintage of this mineral and salty sparkling white is the 2017 Izar-Leku, which was produced with a blend of 90% Hondarrabi Zuri and 10% Hondarrabi Beltza grapes from 20- to 60-year-old vines in Zarautz on sandy slate and clay soils. It fermented in stainless steel, and one-third of the volume matured in barrel with lees for six months before it was put in bottle to referment and spend an additional 36 months with lees, much longer (double the time!) than the 2016. It's 12.55% alcohol and has a pH of 3.13 and 8.2 grams of acidity (tartaric acid) and no residual sugar. It has higher acidity, which gives it more freshness; there's only partial malolactic; and the wine benefitted from more time in bottle to polish that acidity. It's yeasty and smoky with finesse and complexity, more than in previous years, given the extended contact with the lees. There are some apple notes, and it's clean and with finesse, with ultra fine bubbles and a lively sensation in the palate. There's more depth and length. It's a clear improvement over the already-excellent previous vintages. 20,000 bottles produced. It was disgorged in May 2021. Izar-Leku Mahastiak is the joint venture between Artadi and cider producer Zapian to produce a sparkling wine in the Txakoli zone of the Basque Country.