Stevia is pretty cool stuff - I used to grow it in my garden (when I had one) along with several varieties of mint and make my own home-grown mint teas with the stevia leaves blended right in with the mint. I'd make ice water with bruised fresh mint and stevia leaves too and that was really refreshing on a hot day - just a touch of flavor.
You can pick a leaf right off of the plant and nibble on it, the sweetness is immediately evident - no processing needed.