Maddy tells me cashew fruit juice is yummy. I'll have to look out for it! The only time I've seen the fruit is in the freezer case of a Latin American grocery store in Oakland, but I decided not to buy it as a frozen product is usually not the best representation of a fruit.
Solution
The red fruit may be the first thing that catches your eye, but the main crop is the suspiciously cashew-shaped seed hanging from it—oh, and wouldn't you know it, acajou sounds a lot like cashew. (The English and French words are both derived from a word in the Tupi language of Brazil.)
Congratulations to yesterday's solvers Trent, Inca, Connor, Jacob C., Maddy, Peter M., and Kate. Thanks to everybody who made a guess!
Ten years later, Dr. Shapiro revived Puzzle of the Day at Proof School, writing each day's puzzle on a name tag. After 600 puzzles or so, he was just starting to feel normal about students reading his chest all the time when campus closed and the puzzle, like the rest of our lives, moved online. New puzzles are posted daily on school days.
Want to catch up on old PotDs? There's an archive currently containing puzzles from March to December 2020.