Zero Waste Citrus Cordial with Lime and Lemon

Thoroughly wash the lemons and limes in warm water, using a vegetable brush to remove any dirt and possible wax. Dry them with a paper towel. Using a vegetable peeler (either 'julienne' or regular), carefully remove the thin zest from the fruits, trying to take as little of the white, bitter part (albedo) as possible. We only want the colorful outer layer, where the essential oils are concentrated.

Transfer all the peels to a large, clean jar (about 1-1.5 liters) or a bowl with a tight-fitting lid. If you are using optional ginger, peel it and cut it into thin slices, then add it to the peels. Pour in all the sugar. Close the jar and shake it vigorously for about 30 seconds to coat each peel with sugar. Then open the jar and gently muddle the peels with the sugar using a wooden spoon or muddler for about a minute. This will help release the oils.

Seal the jar tightly and set it aside at room temperature for at least 4 hours, preferably for 12 to 24 hours. During this time, the sugar, through the process of osmosis, will 'extract' the intensely fragrant oils from the peels, creating a thick, aromatic syrup at the bottom of the jar. Every few hours, you can shake the jar to mix the contents. You will know the process is working when you see the sugar starting to dissolve and form liquid, and when you open the jar, an incredible citrus aroma will rise.

When the oleo-saccharum is ready, prepare the juice. Cut all the previously peeled lemons and limes in half. Using a citrus juicer (manual or electric), squeeze all the juice into a separate container, such as a pitcher. Try to extract as much juice as possible. You should get about 400-500 ml of juice.

In a small saucepan, bring 500 ml of water to a boil. Pour the hot (but not boiling) water into a jar with aromatic peels and sugar. Close the jar and shake it vigorously (be careful, it's hot - use a cloth!) or stir with a spoon until all the remaining sugar is completely dissolved. Set the mixture aside for about 15 minutes to allow the flavors to meld.

Prepare a large bowl or pitcher, and place a fine sieve or strainer lined with cheesecloth on top. Pour the entire contents of the jar (liquid along with the peels) through the sieve. Using the back of a spoon or spatula, press the peels firmly against the sieve to extract as much valuable, aromatic syrup as possible. You can throw the peels in the compost – they have already given all their best.

Into the strained, aromatic sugar syrup, pour the previously squeezed juice from lemons and limes. Mix everything thoroughly with a spoon or whisk until the liquids combine, creating a uniform cordial. If you are using optional mint, you can now add a few sprigs to the syrup and let it sit for 30 minutes for extra flavor, then remove them.

Prepare a clean, sterilized glass bottle or jar with a lid. To sterilize the container, you can scald it with boiling water or wash it in the dishwasher on the highest temperature. Using a funnel, pour the finished cordial into the bottle. Seal tightly and place it in the refrigerator. The cordial is ready to use immediately, but its flavor will be even better after 24 hours of 'marinating' in the fridge.