"This is the one I used but I have immersed the lemon zest for a much longer period to get a fuller flavour!
From JB, who kindly posted this to the BBS: - Here is a Limoncello recipe from the food section of the San Francisco Chronicle of several months ago.
• 15 thick-skinned lemons (Eureka, Lisbon or Citron)
• 2 bottles (750 ml each) of the best 100 proof Vodka
• 4 1/2 cups sugar
• 5 cups water
Wash the lemons in hot water before you start. Remove the peel with a vegetable peeler, removing all white pith on the back of the peel by scraping with a knife, and put the peels in a 4-quart Mason jar. Add 1 bottle of Vodka and stir. Cover the jar, date it, and put it to rest in a dark cabinet at room temperature.
After 40 days, take out the lemon-Vodka mixture. Ina sauce pan set over high heat, stir the sugar and water together and boil for 5 minutes. Let the sugar syrup cool completely in the pan, about 10 minutes. Add the sugar syrup to the lemon-Vodka mixture along with the second bottle of Vodka.
Stir well to combine. Replace the cover on the jar and note the finish date. Return it to the dark cabinet and store for 40 more days.
At day 80, remove the limoncello from the cabinet. Strain the mixture and discard the lemon peel.
Pour into clean, unused bottles with caps or decorative corked bottles. Store the bottles in the pantry, but put one bottle at a time in the freezer until ready to use. "
I tried the recipe, too, and it sure came out well.
Last November, when the Clementines showed fresh in my local market we got a nice flat of them and decided to try the Limoncello recipe on them, hoping that would make Mandrinetto. Clementines have very thin skin, so we ended up just grating it off, as it didn't come off well with a peeler. It turned a lovely orange color, and seemed to be working up quite fine.
After straining a thin layer of rind from the grating came to the top in addition to the expected small bits that settled to the bottom. I didn't think it was going to be possible to rack the clear liquid from between them, so I used a coffee filter in a funnel and strained it all. Came out wonderfully clear, and it's got lovely flavor. It's not as dark in color as commercial Mandrinetto, which appears to have been colored orange, but the aroma and taste are fantastic!