Preheat your cast iron skillet over high heat until it shimmers, about 5 minutes, filling the kitchen with a faint smoky aroma.
Pat the salmon fillets dry with paper towels to remove excess moisture, helping the crust to develop crispy and crackly.
In a small bowl, mix together paprika, cayenne, garlic powder, onion powder, thyme, and cumin to create your smoky spice blend.
Rub a thin layer of high-smoke-point oil over each salmon fillet, coating evenly to help the spice adhere and achieve a good sear.
Generously coat both sides of each fillet with the spice mixture, pressing gently to ensure it sticks and forms a flavorful crust.
Place the fillets skin-side down in the hot skillet. Hear the crackling sound as the spices meet the pan, indicating a good sear has begun. Cook for about 2-3 minutes until the crust is dark and fragrant.
Carefully flip the fillets using tongs or a spatula, pressing slightly to maximize contact. Cook for another 2-3 minutes until the crust is deep golden brown and the fish is opaque and flaky inside.
Squeeze fresh lemon juice directly over the fillets in the pan, allowing the bright citrus to cut through the smoky spice for a burst of flavor.
Remove the salmon from the skillet and let it rest for about 2 minutes, allowing the juices to redistribute and the crust to stay crispy.
Serve your beautiful blackened salmon immediately, with your favorite sides or a simple salad, enjoying the crackling crust and tender, smoky interior.
