Season the shrimp with ½ tsp Cajun seasoning. Set aside.
In a medium size mixing bowl, use a whisk to sift together flour, cornmeal, 3 tsp Cajun seasoning, garlic powder, onion powder, and ground cumin.
In a separate bowl, whisk together eggs and whole buttermilk with a few dashes hot sauce.
Toss the seasoned shrimp with ¼ cup seasoned flour-cornmeal breading.
Dip each shrimp in egg and buttermilk. Toss in seasoned flour-cornmeal breading shaking off any excess. Have nearby a platter to lay breaded shrimp in a single layer.
Heat oil in a medium size dutch oven or deep heavy bottomed pot to 350°F. Don't overfill the pot.
Fry breaded shrimp in batches for 2-3 minutes total, until golden and crispy. Adjust the heat periodically to maintain the temperature of the oil while frying.
Use a slotted spoon to remove to a paper towel lined pan to drain. Repeat until all shrimp is fried. Sprinkle with additional Cajun seasoning immediately after frying, if desired.
Remoulade: in a small bowl, whisk together mayonnaise, buttermilk (if using), mustard, pickle juice and Cajun seasoning until fully combined.
Toast rolls, then assemble: Starting with lettuce, tomatoes, pickles, onion, 6 fried shrimp then drizzle with remoulade. Alternately, dress the roll with mayonnaise.
Serve immediately with hot sauce on the side.