Marinate the squid for about 1 hour before you cook it. Put it in a bowl and add the crushed garlic, a pinch of salt, a grind of black pepper, 1 tablespoon of lemon juice and a glug of the olive oil. Toss it all
Together so that it's well coated in the marinade, cover and chill.
Half an hour before you cook, take your seafood out of the fridge to let it come to room temperature. If using, put the clams in a bowl under a gently running cold tap for about 10 minutes.
Heat 2 tablespoons of oil in a heavy-based non-stick frying pan. Add the spring onion, ginger, chilli and preserved lemon and cook for 2 minutes, then add the prawns and sliced garlic. Cook for 2 minutes, shaking the pan to avoid anything catching and burning. When the underside of the prawns start turning pink add the squid and its marinade and shake again, cooking for a further 2 minutes. Add the drained clams and the rest of the oil and lemon juice, and cover the pan. Cook for about 3 minutes, shaking the pan to make sure everything cooks evenly.
Spoon into bowls. Serve with chunks of bread and lemon wedges.