Get ready to rock everything from cocktails to cake.
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Want to add the perfect kiss of citrus to everything from cocktails to cake this summer? The secret ingredient is easy to make at home but has a sciencey name: oleo saccharum. 

What is oleo saccharum? 

Oleo saccharum may sound like a new-fangled bit of chemistry, but it is in fact a syrup that is a blend of citrus oil and sugar that has been around since the 1600s. An elixir for craft cocktails, oleo saccharum can also be used to make homemade sodas, fancy up lemonade or iced tea, and even as part of a soak for cake layers. It is also a great way to prevent fruit salads from browning while adding a bit of fresh citrus punch. 

How to make oleo saccharum

You can make oleo saccharum with any citrus fruit—sticking to a single flavor or blending two or even three fruits for different flavors. I like to keep grapefruit, lemon, and tangerine versions around, but have made the syrup with everything from blood orange to buddha's hand.

To make oleo saccharum, first gently wash the outside of your citrus, being careful not to disturb the zest or release the oils. Using a wide peeler, peel off strips of the zest, being sure to get as little white pith as possible. Put the peels in a measuring cup.

For every cup of peels, you will want ¾ cup of white granulated sugar. Put the peels in a zip top bag and add the sugar, mixing so that all the peels are coated with the sugar. Press out all the air and seal the bag tightly. Using a rolling pin, roll over the peels and sugar to start releasing the oils. When the mixture in the bag looks wet, set the bag on a plate or in a shallow dish and let sit for 24 hours, being sure to periodically smoosh the bag around to help ensure the sugar is drawing out all the essential oils. 

After 24 hours, cut a small tip off the bag, and squeeze the liquid into a jar to store. You should get about a half cup of oleo saccharum for every cup of peels. Store in the fridge: It should last 2-3 weeks.

How to use oleo saccharum in drinks and baking

To use your oleo saccharum try adding a tablespoon or two to a large glass of sparkling water for a homemade soda or using it to add flavor and sweetness to iced tea or to amp up your lemonade. To make a glaze for cakes or muffins, mix with enough powdered sugar to get the consistency you want, or mix 1:1 with water for a soak for cake layers.

Don't waste those peels! Toss the peels in enough granulated sugar to coat and separate, then spread in an even layer on a parchment-lined sheet pan and put in a 150° oven until crisp and dry. These sugared peels are a great companion to everything from cheese and charcuterie to a cup of espresso, or as a garnish on desserts. Once dried, these will last a few weeks in an airtight container in your pantry.