So...there are a lot of recipes out there for limoncello. A lot. Not to mention, I'm only doing a small batch to test my method, as it were, so which one do I choose? So far, I'm not really going with any of them, but some amalgamation. I say so far, because I've only done the first couple of steps and now it has to sit. Some say that it only has to sit 10 days per waiting period, but closer to 45 days each supposedly produces a better, smoother flavor. I lasted 28 days for the first wait, and am now on the second.
Anyway, here's the mini-batch recipe that I've worked out.
3 large lemons, zested
250 mL (1/3 of a fifth) 80 proof vodka (and yes, that's a bit low, but I decrease the water in the simple syrup to make up for it)
7 ounces sugar (a bit less than a cup)
3/4 cup water
Once you've zested your washed lemons, stick the zest in a glass jar large enough to hold all your liquid, such as a pint-jar. Add to that the 250 mL vodka (I am using Svedka--relatively cheap but decently smooth). Then put it in a dark cabinet and let it sit. And sit. And sit. For hopefully 45 days. If you can. Certainly no less than 10, but the longer the more lemon-y it gets. And some people recommend shaking it every 2 or 3 days for the first week to week and a half.
For the second part, you put the water and sugar in a pan on the stove, bring to a boil (not too hot, lest you caramelize your sugar), and stir until the sugar is completely dissolved. While this is cooling, strain the zest from the liquor. When the syrup is mostly chilled, add it to the liquor and put it back in the dark and let it sit again for just as long. Again, the longer the better, because it's supposed to produce a smoother flavor.
Honestly, our vessel of choice for the limoncello wasn't large enough for the whole amount of syrup. Instead of choosing a bigger bottle, we chose to do half the syrup into the lemon vodka and let the other half steep with the strained out lemon zest in the fridge (note that! unless you want to seal the jar, the syrup must be kept in the fridge!). As it happens, I used the syrup was used for other things (aka, lemon ginger cookies). The end result is certainly more similar to limoncello than lemon vodka, and it isn't ridiculously sweet, so that's nice.
At this point, you will filter the limoncello...or at least that's what they say. We actually didn't, and it doesn't taste like bath water as everyone seemed to be saying. It's a little rough, but that could be just because we didn't leave it alone in the closet long enough. I don't know why everyone seemed to be so against this, but some of the options that come to mind are that they didn't let the sugar dissolve properly in the syrup, or using all the syrup makes a significant difference, or even perhaps they let the syrup sit long enough to be contaminated and things tried growing and/or fermenting in their limoncello.
That said, there is another property that filtering might effect--ability to store in the freezer. Ours froze. Like I said, this may be because of not filtering, or it might be that we didn't choose a vodka with a high enough proof, or it may have been the recipe we followed. Regardless, it seems to be just fine chilling in the fridge.