I think this is what you are looking for. There is a square cross section, black plastic bar between the hinges that detents, holds the door, partially open and then stops the door when it's fully open. One end of the bar goes into the door panel and the other end goes into a rubber grommet in the fender panel. If you look at the other front door you can see how it is located and how it works.
According to my parts diagram this is called
Check, door -- Left -- Part# 68610-53010
You may also need
Bracket, door check -- Left -- Part# 68618-20030
and
Pin, door check -- Left -- Part# 68617-20050
It appears this might not be a DIY job, as the door may have to be removed and disassembled to install.
An online search of used auto part places might turn one up. The original price of the pin was $73 and maybe $3 for the other parts.