I have learned that "plate" is both sara and osara.
The fact that the o can be attached implies to me that it is an honorific o 御.
My dictionary gives the honorific o as 御 but for osara it gives it as お.
Is "plate" written as both おさら and 御さら?
Japanese Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Japanese language. It only takes a minute to sign up.Sign up to join this community
In osara, the o is indeed honorific and it is commonly written in kana as お, but sometimes also as 御. As you are likely aware, there is often some flexibility in choosing between kanji, hiragana and katakana to write any given text.
As for osara, it would usually be written as お皿, because the honorific o is usually written お and because sara is usually written 皿 (this kanji is taught already in third grade of primary school). As I mentioned, deviations are possible, but I would say that 御さら is actually a combination you will basically never come across in real life. (Note that 御 is not taught until secondary school.)
The same would be true about ocha "tea", which will usually be written お茶, sometimes 御茶, rarely おちゃ and never 御ちゃ.