Sprinkle the salmon fillets with Cajun seasoning and sea salt. Heat the oil in a 10-inch cast iron skillet over medium heat until the oil is very hot. 

Carefully place salmon on the hot skillet flesh-side down and cook for 3 minutes. Carefully flip and cook on the skin side for 6 minutes. Continue cooking and flipping until the salmon is cooked through (depending on the thickness of the salmon, this may take an additional 2 to 10 minutes).

Remove the cast iron skillet from the heat and transfer the salmon to a plate.

Allow the skillet to cool until it is no longer smoking. Place skillet back on the burner over low heat. Add the oil and garlic. Saute, stirring frequently, until garlic has softened, about 2 minutes. Add the chopped kale, lemon zest and Cajun seasoning. Cover and cook until kale has wilted, about 2 minutes. Remove cover and continue cooking until any excess liquid has burned off.

Serve Salmon with Garlicky Cajun Kale.