It’s a fascinating fact that in the Middle Ages, the humble etrog became part of a peace treaty. After fighting and losing yet another war, the Republic of Pisa was banned from trading in etrogim in 1329 by the Guelph League of Tuscany, headed by Florence. Etrogim or citrons had always been valuable, in fact, the Spanier merchants, from Frankfurt, became famous for trading in them. And this is strange when one considers the etrog’s sourness and thick skin, in comparison with other citrus fruits. They also need more water than other fruit trees, so their value lies purely in prayer.

Leviticus 23:40 tells us, “On the first day you shall take to yourselves the fruit of the goodly tree, branches of palm trees, boughs of leafy trees and willows of the brook and you shall rejoice before the Lord your God , seven days.’’ Here the goodly tree means the Etrog tree. But why “goodly”? Translated it means, “uncertain” in biblical Hebrew while in Modern Hebrew it is, “citrus”.

Nevertheless Jews believe that because the etrog is both fragrant and has a taste, it is like a righteous person who studies and performs good deeds. Some liken its shape to a heart: the orb of the world; that the etrog represents man’s commonsense. Although some sages believe that the fig was the Tree of Knowledge, many consider that the etrog or citrus medica was that tree.

Certainly it is one of the earliest fruits brought from the east to the Mediterranean. The etrog is said to have originated in Mesopotamia in 4000 BCE and the ancient Mesopotamians revelled in the scent and the all-year beauty of the fruit.

The Egyptians used etrogim for embalming, while the Romans used them to fend off moths. And when the Jews were released from captivity in Babylon, they carried them to Israel. After the Jewish rebellion against Rome in 66CE, Jews were forced to scatter, taking their precious etrogim with them.

But because they possessed knowledge of how to propagate these plants, they became the first classical gardeners devising the cultivation of other citrus.

Now there are rigorous standards to ensure that the fruit is perfect; it must not be pierced or have black spots; and the tree must be older than three years. Sometimes etrogim have a narrowing in the centre. This is satisfactory. But they must retain the pitam — the remains of the stigma — then they are kosher. If this breaks, the etrog is useless, so it must be treated with great care. It is a plant that grows with thorny spines and modern producers physically remove these spines to prevent the fruit from damaging itself in growth.

So after Succot, what should we do with this beautiful fruit? First, I would plant the seeds as this plant will fruit without grafting.

Then it’s possible to make a glorious marmalade but it will need to be extended with other citrus. Or candy it by soaking and simmering the tough pith until soft, then cooking in a sugar solution until the fruit is sweetly tender. But that is hard work.

So why not enjoy the magic of the etrog by making the most delicious drizzle cake, adapted from an easy all-in-one recipe. The fragrant zest is grated and added to the mixture while the golden topping enhanced by a glorious sugar crust. Each etrog should yield a tablespoon or two of juice — make up the rest with lemon juice.

Etrog Drizzle Cake

Serves 8

Ingredients
● 175g margarine
● 175g soft light fair-trade muscovado sugar
● 1 packet vanilla sugar
● 3 medium free-range organic eggs
● 175g self raising flour
● 1 tsp baking powder
● Pinch salt
● Grated rind of 1 etrog
● Drizzle topping
● 125g fair-trade granulated sugar
● 60ml, 2 floz etrog juice or etrog plus other citrus juice

Method
● Line a 900g loaf tin or 18cm cake tin. Oven temperature Gas Mark 4, 180˚C.
● Sieve dry ingredients in a large mixing bowl, add the rest and whisk until mixture is just smooth.
● Drop batter into tin.
● Bake for approx 45-50 minutes.
● Prepare the drizzle mixture, mixing the sugar and etrog juice.
● Leave cake cooling in tin.
● Pour drizzle over cake.
● Remove cake carefully. and serve .