How do you stop banana flower soup from tasting astringent?

I have made banana flower soup 3 times now. The first time it had a nice, unique warming/comforting flavour. The second time it was inedible. The third time it was almost inedible. The recipes I have found call for the banana flower to be soaked in water with a slice of lemon for 1 hour.

Worried that it didn't work last time, I just quartered the lemon and soaked it with the whole thing (squeezed), but still it had that crappy taste (like banana peels).

I noticed this time that it also said use a non-reactive pan, so I did that.

I am wondering if any one can shed some light on what counteracts this taste? I know it can taste nice, and the banana flower is to substantial to waste! Thanks.