Step 1In a deep bowl, cover the garbanzo beans with 3 cups of water and 1 ½ teaspoons baking soda. Soak overnight, and up to 24 hours. The next day, rinse the beans well.
Step 2In a large pot, combine the garbanzos with the remaining 1 ½ teaspoons baking soda. Toast the garbanzos over low heat until the skins start to fall off, eight to 10 minutes. Add the remaining 5 cups water and bring to a boil. Reduce the heat to a simmer and, using a small strainer, skim the foam and skins that rise to the surface. Cook the garbanzos until tender, 35 to 45 minutes, then remove from heat. Leave the garbanzos in the liquid for 10 minute before straining. This makes approximately 3 cups cooked garbanzos. The garbanzos can be made up to a few days in advance; cover and refrigerate to store.
Step 1In a large mortar, combine the parsley, garlic and salt, and smash using a pestle to combine. Add the lemon juice and set aside for two minutes, then add the garbanzos, tahini and water. Using the pestle in a circular motion, whip the contents until combined. This makes a generous 2 cups hummus, which will keep, covered and refrigerated, up to three days.