You'll have to create an image with the contents of the file at the stored path. Either use imageWithContentsOfFile: or imageNamed:, where imageNamed: takes only the filename and caches images, useful for images that are small and appear often in the UI. Also note, that imageNamed: searches for a @2x-Version of the image in iOS4.
imageWithContentsOfFile takes a full path including your app-bundle's path and dose not have a cache. It's intended for larger images that only appear once on a screen.
imageView.image = [UIImage imageNamed:[recipe objectForKey:IMAGE_KEY]];
imageView.image = [UIImage imageWithContentsOfFile:[[NSBundle mainBundle] 
                           pathForResource:[recipe objectForKey:IMAGE_KEY] ofType:nil]];