Drain the chickpeas into a sieve set over a bowl or jug to catch the liquid. Tip the chickpeas, tahini, garlic and yogurt into a food processor or blender and whizz to smooth.
Whizz in a tbsp of the chickpea liquid at a time until you have a nice consistency, then scrape into a bowl.
Stir in a squeeze of lemon juice and season to taste.
