Cut the bread crosswise in half. Then, cut both pieces horizontally in half. Spread the mayonnaise on the cut sides of the bread. Arrange the tomatoes and lettuce on the bottom halves of the bread.
Pour enough oil into a large heavy pot or electric deep fryer to come halfway up the sides, and heat over high heat to 360?F.
Combine the cornmeal and Essence in a shallow bowl. Add the oysters and shrimp and toss to coat evenly. Shake off any excess cornmeal. In batches, without crowding, deep-fry the seafood, turning frequently, until golden brown, about 2 minutes. Using a slotted spoon, transfer to paper towels to drain.
Arrange the warm oysters and shrimp on top of the lettuce and tomatoes, season to taste with the hot sauce, and top with the remaining bread. Serve immediately.
Yield: 2 large sandwiches