We’re pretty sure that Greco is the only place in the Back Bay where you can eat lunch next to a miniature olive tree. But choosing a lunch place because of its tree selection would be a pretty weird thing to do. What wouldn’t be weird, though, is choosing a lunch place because it makes great gyros. Greco does that, along with some doughnuts that are among our favorite desserts in the neighborhood. It’s a fast-casual place that gets pretty busy during lunch, but you can order online.