Preheat your cast iron skillet over medium-high heat until it shimmers and is hot to the touch, about 2-3 minutes.
Pat the salmon fillets dry with paper towels to remove excess moisture, which helps achieve a better crust.
Brush both sides of each fillet lightly with vegetable or canola oil to promote adherence of the spice mix and prevent sticking.
In a small bowl, combine paprika, cayenne, garlic powder, onion powder, thyme, salt, and black pepper. Mix well to create your spice blend.
Generously sprinkle and press the spice mixture onto both sides of the salmon fillets, ensuring an even coating that forms a crust.
Carefully place the fillets skin-side down into the hot skillet using tongs. You should hear a sizzling sound immediately.
Cook for 3-4 minutes until the spices darken and the fish releases easily from the pan without sticking.
Gently flip the fillets with tongs and cook for another 2-3 minutes, until the flesh turns opaque and flakes easily with a fork.
Remove the salmon from the skillet and rest for 2 minutes on a warm plate. Squeeze fresh lemon juice over the top for brightness.
Garnish with chopped parsley or chives if desired, then serve immediately with your favorite sides.
