To prepare the shrimp tacos: Whisk together the buttermilk, 1 tablespoon of the seafood seasoning, and the salt and pepper in a medium bowl. Add the shrimp, cover, and let soak, refrigerated, for 10 to 15 minutes. While the shrimp is soaking, make the fiesta slaw.
After the shrimp have soaked, whisk together the cornmeal, flour and remaining 1 tablespoon of seafood seasoning in a shallow dish or clean paper lunch bag. Drain the shrimp, shaking off any remaining marinade (discard the remaining marinade). Working in batches, place a few shrimp in the cornmeal mixture and flip or shake until they are coated. Transfer the shrimp to a clean plate or baking sheet. Repeat until all the shrimp have been coated.
In a large cast-iron skillet over medium-high heat, pour 1 inch of canola oil. Heat to about 375 degrees. Add the shrimp to the skillet a few at a time. Fry on each side until golden brown all over, 2 to 3 minutes. Remove to a cooling rack set on top of a baking sheet. Repeat with the remaining shrimp.
Toast the tortillas in a cast-iron skillet or over an open flame. Add a few shrimp to each tortilla and top with the Southern slaw. Serve with the lemon wedges.
To prepare the Southern slaw: In a large bowl, whisk together the mayonnaise, sour cream, lemon juice, hot sauce, paprika, salt and pepper. Add the red and green cabbage, parsley, carrot and green onions and toss to coat.
