Combine the ingredients for the remoulade in a bowl and mix well to incorporate. Store in the refrigerator.
Combine the cajun seasoning ingredients and mix well.
Remove the shrimp from the brine/marinade. Thread the shrimp onto flat skewers. Season with the cajun seasoning on all sides.
Grill the shrimp until slightly charred. Flip the skewers and continue grilling until the shrimp are opaque, and the internal temperature reaches 140ºF. Toast your french bread on the grill.
Build the sandwich. Start by spreading the bottom half of the bread with the remoulade. Top with tomato slices, then iceberg lettuce. Layer on some of the pickles. Top with the grilled shrimp and the top half of the French bread.