Soak chickpeas overnight in 3 cups cold water.
Place chickpeas, bay leaf and cinnamon in a large saucepan with 2 litres cold water and bring to the boil. Simmer uncovered for 1 hour until chickpeas are soft, then drain well and reserve cooking liquid. Discard bay leaf and cinnamon stick. Process chickpeas, 1/4 cup of reserved cooking juices and lemon juice, tahini, garlic and olive oil in a food processor until smooth. Season to taste with sea salt and ground peppercorns.
Makes about 3 cups.