Cover chickpeas and their canned liquid with ½ an inch of water in a sauce pan. Add the baking soda and bring to a boil. Boil until chickpeas are hot and soft, about 5 min. Drain and rinse in hot water.
While chickpeas boil, in a food processor combine the lemon juice, garlic, salt and tahini. Pulse and then let sit until the chickpeas are cooked.
Add the chickpeas to the food processor with the cumin and blend until smooth, scraping the bowl as needed. Drizzle in a tablespoon of hot water at a time, until desired consistency is achieved. Serve warm or at room temperature. Drizzle with olive oil if desired.
Can be refrigerated up to a week.
If you are making this with dried chickpeas, add 1 teaspoon baking soda to your soaking water. Rinse before cooking. Add the teaspoon of baking soda to your cooking water as well, and cook until quite soft, but not completely broken down. Rinse and proceed with blending the recipe.