Every year I read about festivals, etc. in Spain and I see the ground littered with little boxes that look like juice boxes, which are single-serve sangria in boxes. I Googled and searched here, to no avail. So please tell me if you know, what is the "Budweiser" of sangria in Spain? Mainly curious, not trying to become a boxed-wine expert!
And I am aware that sangria is something most Chowhounds make themselves, just as I would if I wanted good sangria.