This is the place to post questions and discussions on usage and style. The members of the Wordwizard Clubhouse will also often be able to help you to formulate that difficult letter.
Most people around here would call those "sushi plates". Google "tasting menu". They are often used to serve this type of meal , as well and are called "tasting plates".
trolley : Thank you very much.
Tho if you were talking with someone who doesn't get out much (like me), it would probably be a good idea to call it a "small, rectangular plate" & then say what was served on it. A sushi plate or tasting plate would mean nothing to me.
End of topic.