Combine flour and Cajun seasoning in a shallow dish.
Heat oil in a large nonstick skillet over medium-high heat to. Dip tomato slices in buttermilk then dredge in flour mixture. Fry tomatoes, in batches, 2 minutes on each side or until golden. Drain on a wire rack over paper towels; set aside.
Split baguettes and arrange with split sides up on a baking sheet. Broil 5 inches from heat 2 minutes or until lightly toasted; remove from oven.
Spread cut sides of rolls with mayonnaise; place fried green tomatoes on bottom roll halves. Top evenly with bacon, avocado and lettuce; sprinkle with hot sauce, if desired. Top with remaining baguette halves and serve immediately.