Soak chickpeas overnight and cook in a pressure cooker until soft. You can use canned cooked chickpeas instead.
Drain and reserve the liquid.
Extract 2 tablespoons juice from the lemon.
Puree the soft cooked chickpeas with lemon juice , peeled garlic, sesame seeds or tahini paste, olive oil and salt until smooth. Add enough of the drained water to get a thick paste which will be easy to spread.
Transfer to serving bowls and garnish with olive oil, a sprinkling of chilli flakes (optional), and some sliced olives.