This makes a wonderful dip for vegetables and, of course, pita bread. If you cook your own chickpeas, make sure they're very tender.
If using canned chickpeas, drain them, reserving the liquid, and rinse them. If using dried, cooked chickpeas, drain them and reserve 1/2 cup of the cooking liquid.
Purée all the ingredients in a food processor until very smooth, adding the reserved liquid as needed. You should have a medium-thick paste (if it's still too thick, thin it more with water). Season with salt. Transfer the hummus to a shallow bowl, drizzle with olive oil, and sprinkle with cayenne. Serve with pita bread or raw vegetables.