I did the "Chianti Wine and Food Safari" with WalkaboutFlorence in July, 2015 and had a fabulous time. Wonderful wine at three vineyards, and delicious food at a restaurant in the Chianti countryside (where we were told "George and Amal dined here twice recently..."). AND: I am an ovo-lacto vegetarian! When I booked the tour, I made a note in the message that "I do not eat meat or poultry, but am sure that with the bread, cheese, and wine, I will be very happy!" Well, lo and behold, when our group arrived at lunch, I discovered that they DID make a special meal for me, and it was delicious! While I was surprised, the tour leader (who was delightful, magnificent!) said: "We just don't want to get besieged with lots of special requests for meals, but we do what we can, when we can..." So, I don't think that that was a promise to create a vegetarian meal for everyone who asks, but, you could gently inquire (say: "Jane from New Orleans told me of the wonderful veggie meal she had on your great tour this past summer...") and see what happens!
Another thought: Book a tour with ToursbyRoberto, in which you will likely go (as I did, 3 summers ago) to lunch at a carefully chosen great village restaurant, where Roberto will order food that the participants pay for, together. There was plenty of fabulous lacto-vegetarian food for me and my sister, at that meal. You could talk with Roberto beforehand about being sure that your palate will be happy with the offerings he plans...
