I've steamed bananas to ripen them- it works. Also here is a trick for ripening avocados
Many years ago a savvy cook from California told me to simmer avos in water to make them ready to use. I never seem to be able to get ripe avos when I am craving homemade guacamole so I have used this tip many times. Just pierce avos (as if you were baking a potato in the microwave) and simmer until soft. Cool and use.
