There seems to be a bit of quite unnecessary acerbity in this discussion. We are all trying to get to the same goal. It seems that "how you cook an egg" attracts assertions of inaccuracy and unnaturalness. I don't see why. The use of you in English and je in Dutch seems quite appropriate, as both can serve as generics. As for unnatural, I can think of dozens of examples involving How do you do X questions or statements - anything from "How do you get to London from here?" to "Look what he just did! How do you think you can get away with that" (where we move from the specific "he" to the generic "you" in adjacent sentences. It isn't unnatural. It's what we do.
"Everyone knows how you cook an egg" sounds quite unnatural in English. A better phrasing would be "Everyone knows how TO cook an egg". Otherwise, the sentence seems to indicate that "Everyone knows how YOU cook an egg", i.e. probably badly or in a wrong way.
I suggest to revise this sentence.