This New Orleans specialty is built on massive, round loaves. They are crusty, but have a soft, light crumb. Do not let their scarcity deter you from making this sandwich. Any large, crusty loaf will work (just choose a lighter, more yielding bread).
Combine well in a medium bowl:
Let the mixture marinate at room temperature for at least 30 minutes before using, or store in the refrigerator for up to 2 weeks. Split horizontally:
Remove some of the soft inner bread, creating a cavity inside each half. Drain the olive mixture, reserving the marinade. Brush the insides of both halves of the loaf generously with the marinade, then spread half of the olive mixture in the bottom half. Add in layers:
Top with the remaining olive salad. Cover with the top half of the loaf and wrap tightly in plastic. Place on a large plate, cover with another plate, and weight down with several pounds of canned goods. Refrigerate for at least 30 minutes, and up to 6 hours. To serve, cut into wedges.