Peel the garlic cloves, cut each one in half lengthways and remove the green germ from the centre.
Place the garlic into a ziplock bag and freeze for at least 4 hours. This step is essential and cannot be skipped.
Measure out the salt, lemon juice, ice cold water and oil before starting.
Add the frozen garlic, salt, lemon juice, all of the water and half of the oil into a tall immersion blender jug.
Blend continuously for 1 to 2 minutes until the mixture is completely smooth and combined.
While the blender is still running, very slowly drizzle in the remaining oil in a steady stream.
Continue blending until the mixture thickens and transforms into a fluffy, pillowy garlic sauce.
Stop blending once the toum is thick, smooth and holds its shape.
Transfer to a jar and refrigerate until ready to use.