Pre-heat oven to 400 degrees F.
Heat a cast iron pan over medium heat and melt 1 tablespoon of butter in the pan.
Pat the salmon fillets dry with paper towel. Coat the top in the cajun seasoning.
Once the butter is melted and starts to bubble, add the salmon filets, skin side down to the pan.
Let the salmon cook for 3 minutes and don't flip it! As it cooks, spoon some of the butter overtop.
After 3 minutes, place the whole pan into the oven to finish cooking the salmon
Depending on the size of the fillets, it will take another 10-13 minutes to cook in the oven.
Salmon is done when an instant read thermometer in the thickest part reads 145F or the thickest part flakes easily with a fork.
Serve immediately on rice with lemon wedges. Squirt some lemon juice overtop the fish before eating.