Peel and cut very finely your onions (if you have a mandolin do not hesitate to use it).
Melt 1 tablespoon half-salted butter in a large skillet or saucepan over medium heat. Add a tablespoon of olive oil.
Fry gently your onions in this butter for 3 minutes. The idea is to have something very melting and translucent but especially no color. Work on a fire not too strong.
As soon as it's cooked, take out your stove from the heat and add your coconut that you grate on the moment. The idea is to have 1/5 of coconut for 4/5 of onions. It is important that you still feel coconut so I leave it to your palate to adjust the right amount of coconut.
Detach the endive leaves that will serve you to welcome the preparation onion-coconut.
Arrange the equivalent of a small tablespoon of your onion-coconut blend in each endive leaf. Season with a little fleur de sel and a little green curry powder. You can also add some chervil or other leaves on top.
Serve immediately and treat yourself to the contrast between raw and crisp cold endives and warm, melting onion-coconut!