Place the garbanzo bean flour in a mound in a large bowl
Add the lukewarm water very slowly while mixing and dissolving the flour with a wooden spoon to form a homogenous mixture. Be careful to mix thoroughly to avoid the formation of clumps.
Let it sit for at least 4 hours at room temperature.
Every 2 hours, use a skimming spoon to remove the foam that has formed at the top of the mixture, then stir the mixture.
After 4 hours, add the salt and half of the olive oil, then mix everything well.
Add the remaining ½ cup of olive oil to a 15-inches round baking pan, making sure to cover the entire tray (called a testo, the traditional tray used is one made of tinned copper; an alternative to this is aluminum).
Turn on the oven to 500F.
Pour the mixture through a strainer and into the pan. Mix until everything is homogeneous and thin.
Put the pan in the oven and cook it until the mixture turns golden (about 20 minutes, depending on the oven).
Turn on the broiler until the surface develops a crust that is light-brown hazelnut in color.
Remove it from the oven and sprinkle with ground pepper. After a minute of brief cooling, cut it in squares and serve it warm.
It is usually served with cooked vegetables, but it can also be eaten as is.