Empty chickpeas into a pot and heat until warm, then drain. If feeling old school, mash chickpeas into mixing bowl by hand. If not, use your handy-dandy food processor to reduce chickpeas into a puree or a mash. I personally like to add the cumin and garlic at this point so it has a chance to cook into the hot chickpeas, mellowing the flavor. After thoroughly mashed, mix in this order tahini, lemon juice, salt, and olive oil.
What you are doing in this recipe is add the thickening ingredients first then adding olive oil to thin hummus to desired consistency. Check for thickness and flavor. Should taste warm and feel medium bodied at this point. If paste is very thin and watery, mix in more lemon juice because the lemon juice acts as a thickener. If paste is very thick, add more olive oil.
At this point, you have two choices: put the paste on the stove at a low heat, cover, and allow flavors to work together. Afterward, chill and serve with a healthy portion of olive oil floated on top. Or if you are happy with it, proceed to serve as is with a healthy dose of olive oil floated on top.