Make Syrup - (Can be made ahead and stored in the fridge.) In a saucepan, add 1 cup (240ml) of water to the sugar and bring just to a boil. The sugar should be mostly dissolved. Take off the heat and cool to room temperature. Refrigerate if not using right away.(In a pinch for time? You can skip making the syrup and it will still be good. Just stir all of the water, sugar and lemon juice together, and go to step 3.
Stir in the lemon juice and remaining water(2½ cups, 590ml).
Freeze - Pourinto one or more freezer proof containers (see notes). Fill no more than halfway full so they have room to expand. Cover and place in the freezer.
Stir & Rake - After about 2 hours, check on it. Quickly scrape down any ice from the sides and rake the bottom with a fork, distributing the ice within the liquid. At this point, it may look like glaciers floating in a lake. Don't worry if they are big glaciers. (Note, depending on temperature and volume, it may take up to 3 or 4 hours before ice starts forming.)Repeat every hour or 2, until the granita becomes crisp crunchy crystals, or according to your preference. (If you like a slushy granita, see last 2 notes.) It usually needs to be raked and stirred less often at the beginning, and more often as the freezing progresses.
To Serve, scrape the granita with a strong fork or spoon before serving, if needed. Serve in cold glasses. Garnish with a little lemon zest tossed in sugar, or a sprig of fresh mint.
Notes
Using an Ice Cream Maker (Gives a smoother texture similar to sorbet) Pour in the chilled mixture and churn until frozen, about 30 minutes, checking on it at the 15 minute mark and, if necessary, giving it a stir with a wooden spoon to get it churning again.
Lemon Juicing Tip: To get more juice out of them, roll the lemons on the table with pressure before juicing.
To Make a Sweeter Granita: Try adding more sugar in 1/4 cup (50g) increments, up to 3/4 cup (150g).
Variations:
Zest of Lemon - Add zest of 1/2 an organic/untreated lemon (or washed well by rubbing with baking soda) to the lemon juice.
Fresh Rosemary - Add 2 Tbsp fresh rosemary leaves to the simple syrup after coming to a boil. Immediately remove from heat and let steep covered for approximately 10 minutes. Strain and let cool completely, then proceed as usual. To serve, garnish with rosemary sprig.
Orange Blossom Water - Mix 1 Tbsp in with the lemon juice.
Freezer Containers: Any kind of container (metal, glass, plastic) or size will do as long as it is not filled too high, since granita will expand when raked. And the more shallow the dish is filled, the faster the granita will freeze. I often divide it into 2 (or more) containers. Ones with lids are very convenient.
Storing: Granita stores well in the freezer for up to 2 weeks. The syrup tends to separate from the ice as time goes by.
To help keep granita from freezing rock hard, and easier to serve the next day, be sure to keep stirring every hour or so until it is frozen into dry crystals. If you like your granita slushy, you can then let each individual serving thaw to a slushy consistency again.
If your granita freezes rock hard, you can either let it thaw a bit before raking with a fork, or with a little more work, you can scrape it immediately into fluffy snow.