Heat the oil in the base of a tagine or a large, heavy-based saucepan over a medium heat, stir in the onion and garlic and cook for 2–3 minutes to soften a little. Add the squid, stir to coat well and cook for 2–3 minutes, then add the olives, cinnamon, bay leaves and sugar.
Pour in the wine and bring to the boil, then reduce the heat, cover and cook gently for 35–40 minutes until most of the liquid has reduced and the squid is tender. Season with salt and pepper and stir in the herbs. Serve immediately with lemon wedges and chunks of crusty bread to mop up the sauce, if liked.