As per a "中学{ちゅうがく}漢字{かんじ}ドリル" textbook used by native speaker students in Japan, this is the 音訓 readings specified for "肉" and "皿":
肉
音: ニク
訓: none given
皿
音: none given
訓: さら
Yet, at denshi.org this is the information provided: 肉、皿。
So, I trust my textbook. Native speakers get to decide the specs of their own language. But, I'd still like to double check this. In fact, I don't ever want to use denshi.org again. A native speaker I trust says the site is managed by non-native speakers. I continue to use it only because it gives we quick response times (and out of habit).
(1) what is going on with those readings 肉 and 皿? Which source is wrong?
(2) what is the official character dictionary that native speaker scholars use? A name, and a link, would be very useful to me.