Food in New Orleans causes lots of arguments. Like when you are in line at the neighborhood po'boy shop and arguing whether to go with the fried oyster loaf or the fried shrimp. This argument is internal, and results in a series of interior negotiations and deliberations until compromise is reached: half oyster, half shrimp. One sandwich, both cravings assuaged. That’s why this is called The Peacemaker — it helps you make peace with yourself.
Use medium-sized oysters and large shrimp for the best result. The key here is to make sure the crispy coating on the shrimp and oysters is neither coarse nor mealy. Corn flour does the trick beautifully. Finally, I like to use Crystal hot sauce, but as this sandwich is called The Peacemaker, I’d rather not argue. Use any hot sauce you’d like.
In a small bowl, stir together the mayonnaise and hot sauce, mixing well. Set aside. Heat 3 inches oil in a deep fryer or deep cast-iron frying pan to 375 degrees. Meanwhile, line a baking sheet with waxed paper.
In a large bowl, stir together both flours, cayenne, salt, and pepper, to taste. Pour the buttermilk into a second bowl, add the shrimp, toss to coat, and let soak for 1-2 minutes.
Then, working in batches, scoop the shrimp out of the buttermilk, allowing the excess liquid to drip back into the bowl, and add to the flour mixture. Toss to coat evenly, then shake off the excess and place on the baking sheet.
When all of the shrimp are coated, repeat the process with the oysters. (It is important that you soak the shrimp in the buttermilk first, as the oysters tend to, for lack of a better term, and because this is a New Orleans specialty, make the buttermilk funky.)
Again working in batches to avoid crowding, add the shrimp to the hot oil and fry until golden brown, about 1 ½ minutes. Using a wire skimmer or slotted spoon, transfer to paper towels to drain and keep warm. Repeat with the oysters, frying each batch until golden brown, about 2 minutes, then drain on paper towels.
Smear a liberal amount of the mayonnaise-hot sauce mixture on the bottom of each bread piece, then place 3 or 4 each of the hot fried shrimp and oysters on top. (If you want a little more spice, hit the shrimp and oysters with a few dashes of hot sauce, straight from the bottle.) Top with the lettuce and tomato slices and then the bread tops and serve.