He eventually figured out that I wanted to eat dinner and that I didn't want a coffee to go, and so he gave me a seat in the corner, from which I creepily watched everyone eat delicious things. When the waiter asked what I wanted (same guy as before) I managed a similarly fluent combination of sounds, and then pointed at a random part of the menu and read it out loud. This flawless method yielded me the most delicious pizza ever ever ever (seen below) with prosciutto and mushrooms.
I gather that pizza is not served sliced in Italy (at least this one wasn't sliced), so I creepily spied on my neighbors, saw them gracefully eating the pizza, and then managed some combination of cutting and picking up and slurping and being very very happy. I wasn't actually very hungry when I walked in the restaurant, but of course I ate the whole thing. And when he asked if I'd like dessert, my brain said "No thanks, I'm very full." My mouth, however, said "Tiramisu, per favore," which was brilliant decision number 2.