We stopped at this very tiny food stand on the way back from the National Park. Almost everyone else was closed, but this little truck was a hidden gem and open past 6!
As you are going north, just past the lava tubes and Hana airport road, a tiny white food truck sits in a muddy parking lot just off the Hana Hwy on the right. We decided to park on the road just in case our rental car could not make it, but that was probably not necessary.
We both ordered Thai food entrees that were whipped up from the garden produce and chickens. The nice lady running the food stand talked to us for a while about her garden and how everything she uses she tries to grow on her farm.
There was a little fruit stand as well.
The decor has changed a little since the other user photos above but it is the same stand. I think maybe they have just moved to a better spot on the road that is more visible.