I saw on egullet where "freeze-dried" fruit is pulverized in the blender, then added to
things, like marshmellow or icing toppings. Fruits such as freeze-dried raspberries, strawberries, mango and lemon. I've tried the first two...works well, although much more bitter than I would have expected. Unfortunately, I could never find freeze-dried lemon.
I found a variety of freeze-dried fruits at Whole Foods in the produce/ bulk area section of the store.