Cook the chickpeas for about 4 minutes in a saucepan over a medium heat, leave to cool then drain.
Place the onions and garlic on a greased roasting tray.
Bake in the preheated oven until soft, about 10 to 15 minutes. When onions are soft, add tablespoon of balsamic vinegar and sugar to roasting tin and mix in onions. Continue to roast until brown and some are slightly crisp.
Combine the chickpeas, tahini and onion mix in a food processor and blitz until smooth. Taste mixture and add lemon juice to taste (I use a whole one).