For years I wondered how to cook banana flower and always imagined it would not taste very good. In Java I ate some delicious food and upon asking what it was, discovered it was banana flower. Now, my wife cooks it regularly. Here is how she does it.
First peel off the tough outer petals until the flower is light coloured.
Then slice in half lengthwise.
Boil in salted water until the halved flowers turns grey (about 15 minutes)
Discard water.
Slice flower into small pieces.
Boil again with salted water until tender.
Add a paste of spices fried in oil (garlic, onion, coriander, black pepper, lemon grass, tamarind, chili pepper, turmeric) and continue boiling for 5 minutes.
Add coconut milk (second and third squeeze) and boil 5 more minutes.
Turn heat to low, wait until boiling stops and then add the first squeeze of coconut milk.
Serve on rice, but accompany this food with fried tempeh. You could also throw some chicken into the banana flower water for your protein.