Self studied courses during my PhD. How to fill the relevant courses section in the CV?
I think that my lack of relevant coursework will be a huge negative in my applications.


I seriously doubt this. While I cannot speak to all cultures and fields, I find it hard to imagine that anyone will doubt your ability to understand and teach underwater basket weaving if you have published original research in underwater basket weaving.

So, I would not give this undue weight in your mind, and certainly not in your application. In particular, I really recommend against raising this issue in your application, and certainly not in a prominent place such as your introductory paragraph. Your application should focus almost entirely on your research. A rule of thumb is that successful post-docs act like faculty members while unsuccessful post-docs act like students -- and giving undue weight to coursework risks placing yourself in the latter group.