re: #587 The Ghost of a Flea
Dried limes, aka black limes, aka Loomi/Lumi [Arabic] or Amani/Ormani [Farsi]. Used in Middle Eastern and Persian food. Never used them for lemonade, though—am curious to try.
If you can’t find it, try sumac instead—bright lemony taste without less citric acid kick—which serves as a substitute in regional cooking.
I cook a lot of Persian food, so I can definitely vouch for the yummy goodness of dried limes in stews and sumac (esp. on kebab, nom, nom, nom).