Heat barbecue hotplate and drizzle with olive oil. Cut prawns and squid into small pieces. Finely chop cabbage and shallots. In a large bowl, mix flour, egg and water. Add cabbage, shallots and drained corn. Ladle batter onto the hotplate and place a handful of prawn, pork and squid onto each pancake. Cook until golden then flip and cook underside until meat is cooked through. Serve hot with bonito shavings, shredded nori, mayonnaise and okonomi sauce.