We are about to embark on a greenfield development using Go for the API tier and would like to use something like Cucumber or Gherkin to develop the specifications along with non-technical stakeholders.
What are our options here in terms of tooling?
This is really too broad of a question and may get closed.
But... A little Googling is all you have to do:
https://golanglibs.com/top?q=bdd
Disclaimer: my BDD package is 9th on that list:
https://github.com/eduncan911/mspec
It doesn't take much to implement your own BDD workflow.
And now with Go 1.7 on the horizon (beta), there are now SubTests that further allow you to encapsulate BDD style contxt grouping and writing with no "package" needed.