Place the chickpeas, cooking liquid, citric acid, and salt in a food processor and process until smooth, about 3 minutes.
Add 1 cup (240 grams) of the tahini and 1/2 cup (120 ml) of the cold water and process for 2 minutes more.
Add the remaining 1 cup (240 grams) tahini and the remaining 1/2 cup (120 ml) water and process for 2 to 3 minutes.
Taste and adjust seasoning with salt and citric acid, if needed.
The hummus should be slightly thin and runny.
Transfer it to an airtight container and refrigerate for 6 to 10 hours.
During this time, the hummus will stabilise, develop a creamy texture, and its flavor will deepen.
The hummus will keep in an airtight container refrigerated for 2 to 3 days.