What is Sebastian's catchphrase 'A Phantomhive butler who can't do this much isn't worth his salt' in Japanese In Kuroshitsuji (Black Butler), Sebastian commonly uses the phrase


  "A Phantomhive butler who can't do this much isn't worth his salt"


It's in about every episode of season one. But it's at least in episode one on 8:38.

I was wondering what this phrase is in Japanese since I can't really make it out from the voice, and I can't find it anywhere else either.
Sebastian's general catchphrase in Japanese is


ファントムハイヴ家の執事たる者、この程度のことが出来なくてどうします?
Phantomhive-ka no shitsuji-taru mono, kono teido no koto ga dekinakute doushimasu?

which can be translated literally to

Those who are qualified as the butlers of Phantomhive, what would they be if they cannot do this much?

... which actually is straightforward compared to the English translation mentioned in the question.
However, that seems like a fan translation, since the official English translation by Yen Press is


I am the butler of the Phantomhive Family. It goes without saying that I can manage a technique as elementary as this.
*Black Butler vol. 1, ch. 1, pg. 8