This is a very popular Middle Eastern dip. It goes well with pita bread and tabouli salad as a good light meal when the weather is warm, or as a side dish with pita and a hot rice or bulghur main course when the weather is cold. Since it keeps well and often disappears in a fraction of the time it takes to prepare it, consider doubling the recipe.
The seasoning amounts are all approximate, which is why I give ranges. When you make the dip, adjust the garlic, olive oil, lemon juice, tahini and salt until you get the level of smoothness or sharpness you want.
Note that you need fresh garlic cloves for this to taste right.
If you leave out the tahini, try increasing the olive oil a little; you will still have a good dip that isn't quite as smooth or rich.
Boil the drained beans for about 10 minutes, then cook the beans with the first group of ingredients until tender (90 min in a pressure cooker, about 3 hours stovetop.) When tender, add salt to the cooking water, stir and let sit 5 minutes.
Puree the chickpeas while still warm with all other ingredients except the tahini, using just enough of the cooking liquid to get a smooth puree. Depending on the amount of lemon juice and oil you use, you may not need any additional liquid. Adjust the ingredients to taste, and stir in a bowl with the tahini when you have the garlic amount you want pureed in. Refrigerate at least an hour for the flavors to combine before serving.