Add the stale bread to a bowl and dampen slightly with water until softened.
In a blender add the garlic and olive oil and liquefy. You will alternate adding the vinegar and bread (which you have squeezed the water out of) and continue pulsing until you get a creamy consistency. If the mixture is too thick add a little more olive oil to smooth out. Also, if the garlic spread is too hot for your liking you may make it milder by adding more bread, olive oil and vinegar.
Finish off by adding salt to your liking.
Pour into a sealable container and chill in the refrigerator for about an hour.