Cut the French bread in half, crosswise. then cut both of the pieces horizontally in half. Spread the mayo on the bread. Arrange the tomatoes and lettuce on the bottom halves of the bread.
Put enough oil into a large and heavy-bottomed pot (or electric deep-fryer) to come up halfway on the sides and then heat the oil over high heat until it reaches 360 degrees F. (Be careful!).
Mix the cornmeal with the Creole seasoning and then add the oysters and shrimp, toss to coat. Shake off any excess breading.
In batches (no crowding), carefully deep-fry the seafood, turning frequently, until they get a nice golden brown, about 2 minutes. Use a slotted spoon to transfer the seafood to paper towels to drain. Repeat until you've cooked all the seafood.
Put the warm oysters and shrimp on top of the lettuce and tomatoes, season to taste with the hot sauce and top with the bread tops. Enjoy!