Just go for the really chunky Belgium "pommes frittes" (something which the Dutch call "patates") to follow the letter of the rule but not quite the spirit of it.
Also, they're amazing!
Edit: turns out the Dutch call them "patate" (also friet and frieten) which I incorrectly pluralized in the French way because I also speak French so it just sounded wrong to me in the singular form and I assumed I recalled it wrong. Thanks to all that corrected me and explained it.
That's how were called in Dutch the delicious chunky, soft french fries that came with a big serving ot mayonaise, which I used to buy back whem I was living in A'dam.
Maybe I incorrectly pluralised it from "patate" or we're both thinking of different kinds of french fries?!
I was under the impression that the plural of that word in Dutch was "patates" since it's originally a French word so the plural is done the French way rather than the Germanic-way (which would yield the word "pataten").
That would be patatten. The Dutch call fries friet or patat (always singular), we (Flemish) call them frieten (plural). The Walloon probably call them frites?
That one showed some of my main problems with the Dutch language: if the word sounds French I process it in French (so patat being singular it just sounds wrong to me, hence it "must" be plural ;)) and when to use double consonants or a single one (I have the same problem in English).
I understand it can be quite confusing. There's a lot of French loanwords, especially here in Flanders, and there's a lot of regional differences, both between Flanders and the Netherlands, and within Flanders. We can pinpoint the province, sometimes city of most native Flemings even if they don't speak true dialect but generic tussentaal.
Like the other commenter said, we generally use the singular form. Though I have heard plural, usually to refer to Vlaamse frieten or Flemish fries. I believe in those cases it's generally meant to be a fun thing to say though