"Possiamo assagiare un po del suo vino e forse ne compriamo una bottiglia?"
I can't claim to have come up with this on my own, but I've used it so many times that it feels like my own. In truth, it was plucked from the pages of Dorothy Gaiter and John Brecher's terrific book, The Wall Street Journal Guide To Wine way back in 1999. Since then it has opened a hundred doors.
Translated it means, "Could we sample some of your wine and perhaps buy a bottle?"
Though this might seem like a transactional phrase intended to shorten the distance between one's lips and the local goodies, when delivered with humility and curiosity, it does wonders to bridge cultural and linguistic divides.
How?
Throughout Italy there is a strong provincial pride in everything from sports to architecture, but most especially when it comes food and wine. And there is no higher flattery a foreigner can convey than an interest and enthusiasm in locally-made treats. Whether it's guanciale from Lazio or Taleggio from Lecco, Italians are (justifiably) boastful of what their hometowns/regions produce. Doubly so when it comes to wine. So, while it's acceptable to order a Barolo when dining in Florence (though you may get some funny looks,) you're far more likely to make a new friend in Bolzano if you inquire about un vino del Sudtirol.
This simple question can both compliment the resident population and give you a huge shortcut to opening a conversation on good footing. That's a travel hack with keeping in your back pocket. What happens from there is up to you and your sense of humor/adventure.
Pro tip: Several easy adaptations of this work for a variety of situations, such as "Posso assagiare un po del vino della casa?" (Could I taste a little of the house wine?) Or the very abbreviated, "Posso assagiare un po?" (Can I sample a bit?) Or, the universally-applicable, "Cosa suggerisci?" (What do you suggest/recommend?)