Alternately:
Select circle brush, set outer size, paint circle, set inner size, erase circle.
Not that the UI isn't terrible.
Select circle brush, set outer size, paint circle, set inner size, erase circle.
Not that the UI isn't terrible.
Edit:
Simpler than this or the linked instructions is to use the Ellipse selection tool with shift to select a circle, then do Edit > Stroke Selection.
Still pretty wacky.
(More and more graphics programs are adopting it.)
Once you're used to it, you can create the ellipse selection and type "/stroke"...
I guess that unless the Gimp developers change their mind and allow for vector drawing inside of Gimp, it's as comfortable as it can get...