Definitely make the Write a Variation more prominent. Also, on the main page you don't even mention that as a feature. To me, there's lots of recipe sites, and having the variation aspect is your differentiator, so shout it out! I'd encourage you to just rip off the Github fork ribbon, because after all, it is proven to work.

I assume you are working on design? Design will be really important. Having fun factor in the design combined with the social aspect of forking recipes could really do well, but you gots some work to do!