Place the salmon fillet on a plate flesh side up. Pat dry with a paper towel.
In a bowl, combine all of the Blackened seasoning ingredients.
In a separate bowl, melt the butter. Brush the butter over the flesh side of the salmon fillet. Sprinkle the seasoning on top of the butter and gently press to adhere to the seasoning.
Heat a large cast iron pan. There is no need to add oil. Once the pan is completely hot, you can tell by drppinga droplet of water and if it starts swirling, it is hot enough.
Place the salmon flesh down and let it cook undisturb for three minutes, or until the flesh is blackened. Take a gentle peek and very gently turn the salmon. Cook the skin side for five minutes.
Continue cooking the salmon on medium heat and cook both sides until the salmon is cooked through. This takes about eight minutes. Slowly turn the salmon on all sides.
Once done, sprinkle the salmon with lemon. Leave the salmon in the cast iron to continue cooking.