DXL - 7:24 am on May 16, 2013 (gmt 0)
A lot of the answers lie in Rich Snippet markup for recipes. See Rich snippets - Recipes
Great stuff. Odd that I never stumbled across that page when doing a Google search on the topic.
It seems just a tad complicated. I took a peek at the source code for a site that shows up as a rich snippet, and it looks a little time-intensive. I suppose it's worth the payoff, though. I may end up hiring someone to do it once to serve as a template.
In the recipe thumbnails pulled, Google tends also to go for finished dishes, rather than for images of preparation.
Is the algorithm that thorough that it can make the distinction?