Heat oil in heavy bottomed sauce pan on medium high heat until it shimmers. Cook the vegetables, allowing them to caramelize. Add the curry, pushing vegetables to the side to allow the curry to toast intensifying its flavor.
Stir in flour to make a roux. Add broth, scraping the bottom of the pan to deglaze and then reduce heat to low and cook for about a half hour. Add the apple. Now add the salt, if necessary (adding salt earlier in the cooking process may cause the vegetables to release their water, steaming instead of caramelizing them.)
It’s important to taste the soup at this point, because with seasoned leftover chicken, you might not need salt at all. Cook another 10-15 minutes, until apples are tender.
Finally, add coconut to finish.