If the Dragon Didn't Bother You, the Potato Shouldn't Either
A usual discussion I see among readers (and show viewers) from fantasy media is the "lack of logic" at the existence of stuff like potatoes or tomatoes in a medieval fantasy inspired in Europe because they were originally from South America.
And honestly, I know it's cool when authors add some real context to an explanation of something "illogical", but the truth is... this is a world with magic, dragons, elves, or whatever you want to put in your fantasy world. It's not historical. There were no real dragons in Medieval Europe, and there were no potatoes in Medieval Europe. So if you are adding dragons, you can perfectly add potatoes to your fantasy story.
The characters are speaking English and the protagonist has ideas about consent, individualism, or gender roles that sometimes read like a 21st-century college student instead of a medieval peasant. Everyone at the "medieval" kingdom has perfectly straight teeth, deodorant-level hygiene, and zero smallpox scarring. So why wouldn't you put tomato in a stew? Cool that there are some food historian. This is not history.
If you add "historical accuracy" as the standard, that standard should apply everywhere or nowhere. And once you actually try applying it everywhere, nobody wants that book. Look at GRRM how much he is criticized by a lot of readers with modern standards. They can't accept how normal was to marry off a twelve-year-old to an old man (and even he writes characters who react disgusted to "normal" practices) and he is declared a pervert or something.
I think that the moment your world has something that can't exist (a sapient fire-breathing reptile, functioning magic, an immortal elf who remembers the last three centuries) you've already left the domain where "but that's not historically accurate" means anything at all.
You're not writing history with a costume on. You're writing a secondary world that merely rhymes with medieval Europe. It borrows the aesthetic.
Want to add a "grounding" explanation? Perfect. Wave your hand and say "oh, traders brought it from the far continent". But don't be scared of making your characters eat potatoes on their way to meet the mighty and dangerous dragon. The potato is just a weirdly specific hill to die on in a genre that's already made a thousand bigger compromises with reality, so add it anyway. Add the tomato too. Add whatever spice, crop, or animal makes your world feel lived-in and your characters' meals feel real.
You definitely don't need to lose sleep over readers who'll excuse a dragon but not a tuber.