Combine the garbanzos, tahini, warm water, olive oil, and juice of 1 lemon in a food processor. Process until smooth and creamy, pausing once or twice to scrape down the sides of the bowl with a spatula.
Add the garlic, salt, cumin, and pepper, and process to blend. Taste and correct the seasoning if necessary. Add more lemon juice to taste. Scrape into a storage container, cover, and refrigerate until ready to use.