"It is pepper."
Translation:Det er pepper.
I had to look it up - because to me (as a native speaker of Norwegian) pepper is neuter and uncountable - but I see the dictionary listing it as masculine. So I wouldn't say "et pepper", but I'd say "pepperet" in the definite form. Not pepperen, but apparently that's allowed.
However, I don't think that's the point here. This "det" would be an "empty subject" of the sentence - like "it" in "it is raining" (det regner). Such an "empty subject" will always be "det" in Norwegian, regardless of the gender of the nouns in the sentence.