Upvote:0
This page seems to be a reliable guide to what you need to do in order to leave and re-enter the US. The key thing would seem to be to have a valid F1 visa, be enrolled in a course (I presume the post-doc counts) and carry the necessary documents, signed appropriately. Your university can probably help too. it's very unlikely you are the first person to have done this.
Upvote:7
The thing you are talking about is called Automatic Revalidation, where people with valid non-immigrant status with I-94 can visit Canada or Mexico (or in the case of F and J status, also Carribean and adjacent islands) for up to 30 days, and re-enter the U.S. and continue their existing non-immigrant status as long as the I-94 is still valid, even if their visa is expired or is single-use and already used.
However, nationals of Cuba, Iran, Sudan, and Syria cannot use it. So you are out of luck.