This is essentially a citron syrup made with citron and sugar, topped up with sparkling water. Ice and mint are good, optional additions for this fragrant, refreshing drink.
Because the fruit will have a different flavor/bitterness depending on how mature it is, it is best to go by taste when you first prepare this drink. For the drink pictured here, I used a ratio of 1 part citron syrup to 2 parts sparkling water.
Do not throw out the pith or the zest. The pith is the sweetest part of the fruit; peel all of the zest carefully, then thinly slice and dress the pith with lemon and olive oil to eat as a salad. (Helena Attlee has a recipe for this Calabrian salad in her wonderful book, The Land Where Lemons Grow, where she tosses it with shallots and black olives, then leaves it to mingle for an hour before serving.) Or, heap it on top of bruschetta with a good pinch of sea salt and lemon juice. The zest can be candied (David Lebovitz has an excellent recipe), but it is also very good for infusing alcohol or making your own "cedrello," limoncello's citron cousin. You can also intensify the syrup for the cedrata (in flavor as well as color) by adding the zest to the pulp. You could also use this citron syrup to sweeten tea, and cedrata is delicious mixed in cocktails, too. —Emiko
Cut open the citrons and remove the pulp. (Save the pith and the zest—see headnote for ideas.) Weigh the pulp, then add it to an equal amounts of sugar (e.g. if you have 7 ounces of pulp, use 7 ounces, or 1 cup, of sugar). Let it sit overnight to macerate.
The next day, pour the sugar, pulp, and any liquid into a saucepan and add the equal amount of water (for example, if the pulp weighs 7 ounces, add 7 ounces of water).
Bring to the boil and let simmer 10 minutes. Allow to cool completely then strain, squeezing the pulp to get everything out of it, into a bottle or a jar. Discard the leftover pulp. This is citron syrup: You can store this in the refrigerator for 2 weeks.
To make cedrata, pour some citron syrup into a glass and top up with sparkling water to taste. Optional: Add ice or mint leaves.