The night before, put the Dried Chickpeas (1 1/4 cup) in a large bowl and cover them with cold water at least twice their volume. Leave to soak overnight.
The next day, drain the chickpeas. Place a medium saucepan or pot over high heat. Add the drained chickpeas and Baking Soda (1 teaspoon). Cook for about three minutes, stirring constantly.
Add the Water (6 1/2 cup) and bring to a boil. Lower heat to medium and simmer for about 20 minutes, skimming off any foam and any skins that float to the surface. Depending on the type and freshness of the chickpeas, it may take a bit longer. Once done, they should be very tender, breaking up easily when pressed between your thumb and finger, borderline mushy.
Drain the chickpeas. You should have roughly 3 2/3 cups (600 grams) now. Place the chickpeas in the bowl of a food processor and process until you get a stiff paste. Then, with the machine still running, add the Tahini (270 gram) paste, Lemon Juice (4 tablespoon), Garlic (2 clove), and Salt (1 teaspoon).
Finally, slowly drizzle in the ice Water (6 1/2 tablespoon) and allow it to process for a full five minutes until you get a very smooth and creamy paste.
Transfer the hummus to a bowl, cover the surface with plastic wrap, and let it rest for at least 30 minutes. If not using straightaway, refrigerate until needed. Make sure to take it out of the fridge at least 30 minutes before serving.
Optionally, to serve, top with a layer of good quality olive oil. This hummus will keep in the refrigerator for up to three days.