Why buy grenadine full of corn syrup when you can make your own so easily? Pomegranate syrup is essentially grenadine, though modern grenadine also usually has some lemon or orange juice added.

Without citrus, the syrup can possibly be traced back throughout the middle east into ancient times, as it was a good way to preserve the juice for use in cooking and medicine. This recipe specifically comes from medieval Andalusia, in the 13th-century Andalusian cookbook. Credit goes to Bill Michalski for converting this into the modern recipe below. The original version (in translation by Charles Perry):

Take a ratl of sour pomegranates and another of sweet pomegranates, and add their juice to two ratls of sugar. Cook all this until it takes the consistency of syrup, and keep until needed. Its benefits: it is useful for fevers, and cuts the thirst, it benefits bilious fevers and lightens the body gently.

Since sour pomegranates are kind of nonexistent where I live, here is a sweet modern version:

8 oz pomegranate juice (1-2 pomegranates)
1 cup cane sugar
Optional: 1 tbsp. lemon juice (if you want grenadine)

Juice the pomegranate(s) (if you’re juicing fresh) until you have 8 ounces. Add the sugar. If you want to make grenadine, add the lemon juice, too.

Bring to a boil and simmer, stirring occasionally, until the liquid is reduced to about half of its volume. You can test a few drops on a cold saucer: if it runs quickly, keep cooking; if it stills, it’s done.