
On closer inspection far and away the most prevalent white varietal is Vermentino. Originally from the Iberian peninsula, Vermentino is now widely planted in northern Sardinia (the link with Spain is also cultural - the port of Alghero has strong Catalan roots and the language is still spoken and even appears on restaurant menus).
Sardinia's only DOCG is Vermentino di Gallura, upgraded from DOC status in 1996. Its typically aromatic, almost bitter palate apparently comes from the soil of sandy clay on a granite base. Check it out!