Pour oil to depth of 1/4 inch to 1/2 inch in a large skillet; heat to 375°.
Whisk together egg and buttermilk in a shallow bowl. Stir together cornmeal mix and seasoning in another shallow bowl.
Dredge crabs in flour, dip in egg mixture, and dredge in cornmeal mixture. Cook crabs in hot oil, in batches, 2 minutes on each side or until golden brown. Drain on paper towels.
Spread insides of rolls with Spicy Rèmoulade. Layer with lettuce, tomato slices, and fried crab.