For the Cajun aioli: In a bowl, whisk together the mayonnaise, lemon juice and Cajun seasoning until combined. Fold in the green onions, cover and refrigerate until ready to serve.
For the fried pickles: Combine the sour cream and pickle juice in a shallow dish. In a second shallow dish, whisk the flour, cornmeal and cayenne until combined.
Drain the pickles and add them to the sour cream mixture. Then, using a fork, add the pickles, a few at a time, to the flour mixture and toss to coat.
Heat 1/2 inch of canola oil to 350 degrees F in a large cast-iron skillet. In several batches, fry the pickles, flipping constantly, until golden brown and crispy all over, 2 1/2 minutes per batch. Drain on a paper-towel-lined baking sheet and season with salt.