In my case, the situation is hiring a remote contractor (an individual contributor, not a company) to perform a well defined task at a fixed price within a specified timeframe.

The job will be closely monitored and controlled to ensure progress is being made, and the job is being done in a way that the final product can be successfully integrated into the code base. The work is central to the company, but may be outside an area of expertise, or an added work item beyond the scheduled capacity.

In otherwords... pretty much any software-related contracted task, done by any bootstrapped startup, ever.