Place the oysters in a small bowl with the ½ cup of milk. Let the oysters soak for about 10-15 minutes.
In a small bowl, whisk together the remaining tablespoon of milk, water, cayenne, and eggs. In another, medium-sized bowl, combine the flour, cornmeal, and salt, and mix until fully integrated.
Fill a large saucepan about half way up with vegetable oil and place over medium-high heat. Once the oil is hot, it’s time to batter the oysters. Take them out of the milk and dunk them in the egg mixture, then, in batches of about 5, drop them into the flour-cornmeal mixture. Cover the oysters in the flour to coat completely and then gently shake off any excess flour.
Next, carefully drop them into the oil, frying only about 30 seconds to 1 minute, or until they are golden-brown. Transfer the oysters to a paper towel-lined plate. Repeat until all of the oysters are cooked.
To assemble the sandwiches, cut the baguette into three 6-inch loaves and then slit them down the middle leaving one side intact. Slather each side of the bread generously with the mayo, add in a little shredded lettuce and a slice or two of tomato. Finally, add the fried oysters, 5 for each sandwich.