Soak the chickpeas for 10–12 hours in the water and salt.
Simmer the chickpeas in their soaking water in a covered pot until they are soft. You can cook them on the stove in a covered saucepan for about 1½ hours, or with an electric pressure cooker (this is my preference) on high pressure for 25 minutes with a natural pressure release.
While the chickpeas are still warm, use a slotted spoon to transfer them to a food processor or high-speed blender. Add ¾ cup of the cooking water, along with the cilantro, garlic, tahini, lemon juice, salt and cumin.
Process the mixture until it is very smooth. If it is too thick, add more of the cooking water, a couple of tablespoons at a time.
Taste the hummus for seasoning, adding more salt if necessary. Transfer it to a container with a tight-fitting lid, and keep it refrigerated until ready to use. It will keep for 3–5 days.