Find models with a specified set of associated models

Hi,

I have a many-to-many relationship between ‘dishes’ and ‘ingredients’.
Now how can I most efficiently search for dishes that have all of a
specific set of ingredients. Say, if I have two ingredients, ‘bananas’
and ‘walnuts’, how can I find all dishes that contain bananas and
walnuts (and maybe others)?

Thanks for any hint!
Ingo