In a medium saucepan, bring water and agave syrup just to a boil, stirring until syrup is dissolved.
Remove from heat and cool for 10-15 minutes.
Add the basil or other herbs and let stand for 30 minutes.
(If using rosemary or lavender blossoms, just stir them in and let it stand, no sieve necessary. They look really pretty in the granita.)
Pour through a fine mesh sieve, discarding basil.
Use a Microplane grater to get just the yellow part of the lemon peel. It's an amazing tool. Or, use a peeler to peel the lemons, then finely shred with a paring knife.
Stir the lemon peel and juice into the syrup.
Pour into a shallow baking dish. (The larger the better; it needs to fit into your freezer and sit flat.)
After about 45 minutes, pull it out and rake it with a fork, breaking up any clumps.
Continue to freeze and rake about every 30 minutes until you have fluffy snow-like ice.
Serve at once, or store in an airtight container.
Notes
Per serving:
91 calories
0 g fat
0 g cholesterol
0 mg sodium
163 mg potassium
23 g carbohydrate
0 g fiber
23 g sugars
0 g protein
2 Weight Watchers Points
Agave syrup is made from the agave cactus. It's a naturally occurring sugar (although still processed) with a lovely light taste, much lighter and more neutral than honey. It's suitable for diabetics because it doesn't raise blood glucose levels the way other sugars do. Make sure you choose an organic brand. Non-organic brands might have fillers like high-fructose corn syrup, or use chemicals in processing. I now use much less agave syrup after learning more about it. You could also make this with honey or brown rice syrup.