Place all the chilli jam ingredients in a saucepan, bring the mixture to the boil and simmer for 45 minutes until thickened and jam-like. Leave to cool completely.
Remove the tentacles from inside the squid bodies and slice the tentacles away from the beak part of the head. Remove the quill from inside each body, if present.
Cut the bodies in half lengthways and then again crossways, then, using a sharp knife, score the inside with a diamond pattern. Place the squid pieces in a bowl. Add the garlic, salt and sugar and rub in well, then leave to marinate for 15 minutes.
Cook the squid on a hot barbecue for 1—2 minutes, garnish with lime wedges and serve with the chilli jam.