Combine crabs and milk in a shallow dish. Cover and chill 1 hour; drain, discarding milk.
Combine flour and next 3 ingredients. Dredge crabs in flour mixture.
Sauté crabs, topside down, in hot oil in a large skillet 1 to 2 minutes on each side. Drain on paper towels. Place each crab on a French roll. Top with Remoulade Sauce, lettuce, and tomato.