Orgeat (pronounced /ɔːrˈʒɑː or ˈɔːrdʒiət/) is a French term that originated in the Latin phrase hordeaceus, meaning 'made with barley.' It started out as a kind of barley water (a barley oil and water emulsion), but over time to improve the flavor almond, sugar, and other flavors were added. Now, orgeat no longer has anything to do with barley. Instead, orgeat syrup is an almond and sugar syrup, usually flavored with either orange blossom water or rose water. It's non-alcoholic on its own, although you can extend its life by adding a bit of liquor (usually brandy) as a preservative.
Orgeat is an important ingredient for a lot of Tiki cocktails, including the Mai Tai. It can also be diluted with water or soda water for a refreshing non-alcoholic drink (sometimes called orzata). You can also play around with flavors, using different nuts (such as pistachio or cashew) or infusing it with fruit or spices.
In recipes from as far back as the mid-1800s, orgeat was made with bitter almonds. However, it's far more commonly made with sweet almonds now. This is largely because bitter almonds are toxic, and potentially lethal in large quantities; they contain cyanide.
What I will be providing instructions for here is a pretty traditional orgeat recipe, using almonds and flavored with orange blossom water.
Almond Orgeat Syrup Recipe
Step 1: Prepare your almonds
If you can find blanched almonds available for purchase, you can certainly save yourself a bit of time by buying them already prepared. However, if they are not available (or are more expensive), you can instead buy regular almonds (make sure they are not roasted/salted; you'll usually find them in the baking aisle) and blanch them yourself.
To blanch your almonds: Bring a pan of water to a boil. Add your almonds and allow to boil for 1 minute.
Strain the almonds and run them under cold tap water to cool them.
Now that you've blanched the almonds in boiling water and cooled them, you should be able to easily remove the skins by simply squeezing them off with your fingers.
Once you've removed the skins from all of the almonds, pat them dry. You're now ready to grind them into a fine almond meal. The easiest way to do this is with a food processor. Simply put them all in and run it on high until they're finely ground.
Step 2: Make Simple Syrup & Add Almonds
In a small saucepan, add your sugar and water. Bring to a boil (sugar will dissolve). Allow to boil for 3 minutes. This forms a simple syrup.
Add finely-ground almonds to the boiling simple syrup. Turn heat to low and allow to simmer for 3 minutes.
Slowly increase heat up to medium-high. When your mixture is nearly at a boil, remove it from the heat and cover it with a lid. Allow it to sit and infuse for at least three hours, and up to eight hours.
Step 3: Strain
Once your almond-simple syrup mixture has fully infused, prepare two layers of cheesecloth. Allow the cloth to drape over a large bowl. Pour the contents of your saucepan into the cloth. Twist and squeeze your cheesecloth to strain all of your syrup out. You should be left with your (somewhat sticky) ground almonds in the cheesecloth and your orgeat syrup in the bowl.
Step 4: Finish & Bottle
Now that you have your strained syrup, it's time to add your final flavor and preservative ingredients. For this simple, traditional orgeat syrup, I added orange flower water and brandy. The brandy adds a touch of flavor, but is primarily an extra preservative to help the orgeat syrup last longer.
Once you have stirred in your orange flower water and brandy, you're ready to bottle your orgeat. It will keep in your fridge safely for at least two weeks, and likely longer (the sugar and the brandy both act as preservatives).