Drain, but reserve the garbanzo beans, pat the beans dry with a paper towel.
In a food processor or blender, add garlic, garbanzo beans, lemon juice, tahini, salt and 1 T olive oil. Add 2 T reserved bean liquid and process until smooth. Add more liquid up to 1/2 cup to the desired thickness you prefer. I like mine of the thick, chunky side so I only about 3T liquid.