If I were you, I'd not be eating star apples from Vietnam. Some one just shared a video of maggots or parasites found inside the star apples from Vietnam on Facebook. H/she bought it from Little Saigon's. The video posted on California Tropical Fruit Growers.
Awesome, bon appetite.
I find that hard to swallow, since maggots or parasites need dead flesh to host their pupate stage.
Even at home with all the fallen fruit and dog $#!+ everywhere I've never seen anything like it in fruits.
It's possible it may be caterpillars of some sort?
The source she received it from probably had poor handling, but I've bought a box, consumed half and haven't seen anything but delicious white milky flesh. Would I still eat it if maggots appeared? You bet! It's a stellar deal to get protein packed in your fruit!
Best way to eat it, refrigerate, roll around with pressure on flat surface, make a incision on the center all the way around the fruit and pry open. It'll come out perfectly and easy to eat with a spoon or just invert the skin to devour. Add condensed milk and crushed ice to preferred amount.