Preheat the griddle to medium-high. Add avocado oil and a sheet of parchment paper to the griddle.
Season the cod with the blackening seasoning and paprika mixture. Cut the cod into 2-inch fillets.
Place the cod fillets on the parchment paper on the griddle. Cook for 3-4 minutes on one side before flipping.
While the cod is cooking, warm the corn tortillas on the griddle over low heat.
Prepare the cole slaw by combining the slaw mix, lime juice, and salt in a bowl. Massage until the slaw softens.
Prepare the mango salsa by mixing the diced mango, Roma tomatoes, lime juice, red onion, cilantro, and salt. (Note: You can make the salsa up to 24 hours in advance and store it in the refrigerator.)
Once the cod is done, remove it from the griddle and start assembling the tacos.
To assemble, spread sour cream sauce on the bottom of each tortilla. Add a piece of cod, followed by the slaw mixture, mango salsa, and a dollop of guacamole. Enjoy!