If the chickpeas are canned, make sure they are thoroughly rinsed and drained.
Put the olive oil, garlic, lemon juice and tahini into the blender and pulse to chop the garlic a bit. Add the drained chick peas and 1/4 cup of the hot water and blend until completely smooth and creamy. If the blender gets stuck or the hummus seems too thick, add the rest of the water as needed. You may even need more. If you add additional tahini or lemon juice, adjust water accordingly.
Put into a container and cover. Let sit for at least one hour for flavors to meld. If longer, put it into the refrigerator.
Best to let it sit for an hour or so to let the flavors meld though it is perfectly delicious immediately in case of hankering emergency. Store in a covered container in the refrigerator. Keeps at least three days. No idea beyond that; mine's never around that long.