Cut the onion into pieces.
Place these slices in a large jar in the following order: one slice of onion, a layer of brown sugar, another slice of onion, another layer of brown sugar, and so on, ending with a layer of sugar.
Cover the jar to keep ants and other insects out, and leave it overnight.
The next day, you will discover the glass filled with a honey-colored liquid, which is the syrup.
One teaspoon of syrup is administered every three hours.