Nice idea but it seems not to always exist: <hr /> [![ConvexTriangulation][1]][1] <br /> <sup> Point $4$'s star is reflex at $3$, Point $3$'s star is reflex at $4$. </sup> <hr /> Here's an argument that those are the only two triangulations. Each interior point ($3$ and $4$) must be degree-$3$ or degree-$4$: degree-$3$ to span more than $180^\circ$, and at most degree-$4$ because there are only four other points. In the left figure point $3$ has degree-$3$ and point $4$ degree-$4$, and in the right figure point $3$ has degree-$4$ and point $4$ degree-$3$. After these choices, the diagonals are forced. [1]: https://i.sstatic.net/SPHxZ.jpg