For more detailed instructions, including Instant Pot directions and troubleshooting, refer to the body of the post.
Before draining chickpeas, reserve 3/4 cup of cooking liquid.
To increase the recipe, soak and cook all the needed chickpeas at once but process them into hummus in batches.
In a large bowl, combine 8 cups of cold water, the chickpeas, and 2 tablespoons of salt. Let soak at least 12 hours, or overnight. Drain and rinse well.
In a large pan over high heat, bring 10 cups of water and the baking soda to a boil. Add the chickpeas, and optional quartered onion, parsley, thyme, and bay leaves if using. Adjust heat to a simmer and cook until the chickpeas are softened. Remove the onion and herbs. Set aside about 2 tablespoons of chickpeas. Strain the chickpeas for one minute, reserving 3/4 cup of the liquid, then transfer to the food processor. Add the remaining 1 teaspoon of salt to the food processor, then process for 3 minutes.
Stop the processor and add the tahini. Continue to process until the mixture has lightened and is very smooth, about 1 minute. Use a rubber spatula to scrape the sides and bottom of the processor bow. With the machine running, add the 3/4 cup of cooking liquid and the lemon juice. Process until combined. Taste and season with salt.
Transfer the hummus to a shallow serving bowl and use a large spoon to make a swirled well in the center. Drizzle with olive oil, then top with the reserved 2 tablespoons chickpeas, parsley, cumin, and paprika or alteratives.
Note: Best served warm; mixture will become a little thicker after refrigeration.
Note on Tahini: Stir the tahini very well. Some brands separate and can become quite thick at the bottom of the container. If your tahini is particularly thick, you may need to add a tablespoon or two of tap water for the hummus to reach the right consistency.