Cook the dry chickpeas: Soak approximately 1½ cups of dry chickpeas overnight (recommended), then drain. Add the chickpeas to a pot and cover with fresh water by 2 to 3 inches. Stir in 1/2 teaspoon baking soda, bring to a boil, then simmer until very tender, 60 to 90 minutes. Drain and rinse. See Notes.
Roast the peppers and garlic: Set your oven to broil and line a large baking sheet with foil. Slice the bell peppers in half and remove the seeds and membranes. Place the peppers cut-side down on the baking sheet along with the unpeeled garlic cloves. Broil for 15 to 20 minutes, rotating the pan every 5 minutes, until the peppers are tender and nicely charred.
Steam and peel the peppers: Remove the baking sheet from the oven and wrap the peppers in the foil (or transfer them to a bowl and cover). Let them steam for 5 to 10 minutes, then unwrap and peel away the skins. Set the peeled peppers aside.
Blend the base: Add the tahini and lemon juice to a large food processor or blender and blend until thick and creamy, about 1 to 2 minutes.
Add the roasted bell peppers: Add the roasted red peppers, 2 to 3 cloves roasted garlic (or 1 small raw clove), 1 teaspoon salt, and 1/2 teaspoon cumin. Process for 1 to 2 minutes, or until everything is fully blended and evenly distributed.
Finish blending: Add the cooked chickpeas, 2 tablespoons olive oil, and 2 to 3 tablespoons ice-cold water. Blend for 3 to 4 minutes, scraping down the sides as needed, until smooth and ultra creamy.
Adjust, taste, and serve: Season with additional salt and cumin, to taste. If the hummus feels thick, add 2 to 3 tablespoons cold water (or 1 to 2 ice cubes), plus more as needed. For extra richness, add a little more tahini.
For best results enjoy within 4-5 days. Keep leftovers stored in the refrigerator.