I have adjusted this recipe from how I first posted it. I decided that it was just too tart. I changed the amount of lemon juice from 1 1/2 cups to 1 cup and like it so, so much better. In fact, I pretty much have kept a container of this stuff in the freezer continuously since I first posted it!
I am always looking for ways to fool myself into thinking I am eating ice cream, but when you have something as good as this, you just don't have to pretend. And while it is still sweet, cold, and smooth, it has no fat. And the taste is so clean and tart. Sorbet is often granular and icy, but this will never be a problem when you add just a tiny bit of guar gum.
I used to snub my nose at guar gum; I thought it was some kind of artificial additive. Well, after finally doing a bit of research, I realized that it is all natural.. no more bizarre than say coffee or nutmeg. Guar gum comes from - imagine that - the guar plant. It grows in Pakistan and India and the beans are harvested and ground up into the product you purchase at the store. Guar gum has some very special properties: it has eight times the thickening power of corn starch and is a great emulsifier (I use it in my vinegarettes). It also helps to retard the growth of ice crystals in ice creams, sorbets, and the like. It has no flavor and makes such a difference in the texture. The only warning is to not use more than the recommended amount. If too much is used it can give things a very odd, slimy texture.
2 cups sugar
2 cups water
1 cup fresh lemon juice
1 TBS grated lemon zest
1/8 tsp guar gum (optional)
Zest and then juice the lemons. Heat the sugar and water together until the sugar is completely dissolved. Cool completely. Add juice and zest and chill in the refrigerator completely. Freeze in an ice cream machine following the manufacturer's instructions. Let process/freeze until it becomes thick and creamy. If in doubt, give it another couple of minutes. Sorbet melts very quickly, especially at this point, so have your freezer container ready. Scoop sorbet into container, put a lid on and let sorbet "ripen" in the freezer. This allows it to firm up so that it won't melt so quickly when it is served. I would give it at least 4 hours before serving.
This sorbet is very tart, if you want it a little less so, simply use less lemon juice. I would add 1 cup of the lemon juice and then start tasting as I add the rest to make sure it ends up the way you want. To get 1 1/2 cups of juice takes about 8-10 medium lemons. I use the cheaper lemons that come in a bag. I can get a bag of 10 lemons for less than $3.00.
This is also a great time to take advantage of all those lemons. Because I don't always have lemons on hand when I need zest, I try to keep dried lemon zest in the cupboard. When I make this recipe, I zest all of the lemons and spread the zest I don't need out on a piece of parchment on the counter to dry. When it is completely dry, store in an air tight container. Use as you would fresh lemon zest.