Pour the chickpeas onto a large plate. Check the chickpeas and remove small stones and other grains or legumes.
Rinse the chickpeas in a sieve, until the water runs clear. Soak the chickpeas in a large bowel of water for at least 12 hours. Change the water a minimum of two times, in order to prevent fermentation of the chickpeas. (The chickpeas should approximately double in size. Make sure to use a big bowl and plenty of water.)
Drain the water and transfer the chickpeas into a big pot with new clean water. Add the baking soda, but refrain from adding the salt. Bring the pot to a boil. Once the pot boils, turn the heat to low and simmer the chickpeas for about 1-1.5 hours. While the pot is simmering, use a big spoon to scrape peels and foam floating on top of the cooking water off. Once the chickpeas are very soft and easily mashed, take the pot off the heat. Only at this point in the process, add salt to the water and stir. Cool the chickpeas to room temperature or colder. Sieve the chickpeas, reserving the cooking water for later.
Put the chickpeas into a food processor and grind well. Add the tahini and the rest of the ingredients to the mixture and continue processing, until you achieve the desired texture. It is best to add the tahini and lemon juice a bit at a time and taste the mixture until you achieve the desired taste. If the hummus is too thick for your liking, add some of the cooking water to the mixture and process.
Serve with some olive oil and chopped parsley as garnish.