Alas, I am defeated. Looks like pausing to consider おねいちゃん was my fatal mistake.
Seriously, though, good call on "potato" vs. "sweet potato"; I always forget that sweet potatoes are the default and ジャガイモ are the 'normal' sort in Japanese.
Sweet PotatoesMinoriko, you're really good at digging up sweet potatoes.I like sweet potatoes!Yes, I do.Do you like sweet potatoes too, big sisser? In the original, "onei-chan", a childish mispronunciation of "onee-chan".Ah, are you steaming sweet potatoes?Make me one too!'Kay.