1) In a large bowl, soak the oysters and shrimp in a mixture of buttermilk and hot sauce for 20 to 30 minutes. In a shallow dish, whisk, together the cornmeal, onion powder, garlic powder, paprika and cayenne.
2) In a deep-fryer or heavy-bottomed pot, heat enough oil to come halfway up the sides of the pot, to 190C.
3) Drain the oysters and shrimp and toss them in the seasoned cornmeal. Working in batches, fry the oysters and shrimp until golden and crispy, about 3 minutes. Remove with a slotted spoon and drain on paper towels. Season with salt, to taste.
4) Split the rolls and smear with Creole mayonnaise. Line with plenty of shredded lettuce and tomato slices. Top with fried oysters and shrimp. Cut each roll into 2 to 3 pieces. Serve with hot sauce and a wedge of lemon.
5) Creole Mayonnaise (Remoulade): Combine all the ingredients well in a large mixing bowl. Cover and refrigerate until ready to use.