Cube the beef and place it in a pan of cold water. Boil until tender.
Peel the bananas and add to meat with the chopped onions. Cover and simmer until tender. Remove the meat from heat.
Add the butter to the bananas, mashing or liquidizing. The consistency of the fiished puree should be like a heavy cream.
Reheat the puree, season and serve separately with the meat. If you use coconut, ad to the banana puree just before serving.