Make remoulade sauce. In a small bowl, whisk together mayonnaise, ketchup, mustard, garlic cloves, pickle juice, Worcestershire sauce, hot sauce, lemon juice, and ¾ teaspoon creole seasoning. Cover with plastic wrap and refrigerate until ready to use.
Season shrimp. In a medium-sized bowl, combine the shrimp with 1 tablespoon of the Creole seasoning.
Marinate. In a large bowl, whisk together the flour, cornstarch, 2 teaspoons of the Creole seasoning, and baking powder. Whisk in the water and egg. Add the shrimp to the batter and let it marinate while you heat the oil.
Heat pan. In a large heavy-bottomed skillet, pour enough oil to be about ½ inch tall in the pan and heat it to 350℉.
Coat. Pour 1 cup of the Panko bread crumbs into a pie pan or wide bowl. Using tongs, remove shrimp one at a time from the bowl, allowing the excess batter to drip back into the bowl. Lay the shrimp flat over the breadcrumbs without overlapping. Pour a couple of tablespoons of breadcrumbs over the top to ensure the shrimp are covered in breadcrumbs. Repeat with all of the shrimp, laying the breaded shrimp on a cookie sheet.
Cook. Cook shrimp in batches in heated oil for about 2 minutes on each side in a single layer. Place cooked shrimp on a paper towel-lined baking sheet with a cooling rack placed over the top to prevent shrimp from getting soggy.
Make the sandwich and serve. On the bottom side of the sliced bread, place the desired amount of lettuce, tomato slices, and pickle slices. Generously add shrimp over the top. Generously spread the remoulade sauce on the other side of the bread and place the top of the bread over the shrimp. Serve immediately with additional remoulade sauce and additional pickles if desired.