Tough to know how to classify some of these pantry items. "Sauce" is not quite right for Saba, which is described on the packaging as a "dressing" - not quite right either. I was first exposed to saba in savory dishes at Dopo. I understood it to be balsamic vinegar which, it turns out, is not exactly true. Saba is the reduced must of trebbiano and lambrusco grapes that has been stored in chestnut or oak barrels for two to three years.
Historically it was used as a sweetener, in the way that folks use honey or even molasses. The taste is akin to honey, though predictably redolent of grapes. The consistency lends itself to pouring in ways that honey does not.
Saba was in use as far back as five thousand years ago, consumed by the usual mediterranean and african suspects. The variety pictured here can be found at Market Hall for about $20.00, and has been produced by the Leonardi family for more than a hundred years.