How to get 'sides' of a simple mesh with indexed vertices (corners)

I have a 3d voronoi ‘rock’ or cell created with ofxVoro. I would like to do something creative with the sides of the rock.

The rock is available as an outline saved as an ofMesh with indexed vertices for the corners, generated as an OF_PRIMITIVE_LINES, so there really isn’t any sorting done.

I would like to take a vertices and build the side as an ofPolyline or ofPath.

I have created a sorted array of the indexes (number one and it’s three joins, number two and it’s three, etc)

Is there an easy method for sorting through all of the connections and finding the ones which link back to the original index, which altogether can be saved as an ofPolygon? Should I be testing each consecutive point to see if it is on the same ‘plane’ as the original indexed vertex and first connected corner?

ofxVoro does have a function getCellsPolylines(), but it returns an ofPolyline where all vertexes are repeated three times (so the first three are identical, the second three are identical)