Preheat the grill to its highest setting.
Place the bread into a food processor and blend into medium-sized breadcrumbs.
Add the remaining stuffing ingredients, except for the parsley, to the breadcrumbs and blend until thoroughly combined. (If it becomes a lump, remove the lid and break it up a little with a spoon.) Stir in the chopped parsely.
For the crayfish, using a sharp knife, cut all of the crayfish lengthways from tip to tail. Remove any waste sacs from the crayfish.
Arrange the crayfish, side-by-side, on a roasting tray. Smear up a generous amount of the stuffing onto the flesh side of each crayfish half.
Sprinkle the crayfish with salt and place under the grill. Grill for 4-5 minutes, or until completely cooked through. The shells will turn completely red when cooked. If there are any remaining signs of dark brown or blue colouring, they are not ready and require a few minutes more.
To serve, transfer the cooked crayfish to a plate, and arrange in rows. Serve with lemon wedges.