How to say "on top of which" here?

Question

It hit me that I don't know how to naturally phrase this...

Basically, the impetus is if I was at a teppanyaki restraunt, and wanted to ask what they referred to the flat grill they use as. So the question would be something like "What do you call that thing upon which you're cooking the food?" I know the words for every part of this sentence, and know a ton of grammar, but this particular sentence seems to be eluding me >.<. Help pls? ;-;

I know there are a zillion workarounds, some that are probably even more natural. For example, "何の上にそれを炒めてますか？" ("what are you cooking that on?"). But I'm intentionally asking how to directly say "what do you call that thing upon which you're cooking". Preferably, I want the answer in a manner that's phrased like "___________は何と言いますか?" For example, if I wanted to ask "what do you call the tool you're using?", that could be translated as "君が使ってるその道具は何と言いますか?"

Answer 1

If I need to use a relative clause, the translation would be:

上で食べ物を炒めているそれは何ですか?
(lit.) What is that thing where you're cooking the food on top?

To avoid any confusion, it may be better to say その黒いの ("that black thing"), 板 ("plate") or something instead of just saying それ.

Japanese has no particle that directly corresponds to the English preposition "upon", so you need to use an adverbial phrase (上で) instead. Even if it had, Japanese relative clauses work by omitting a particle, and there is no way of distinguishing "with which", "in which", "by which" and so on. It's simply impossible to give a word-by-word translation of "upon which".