Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Trim the woody ends off the asparagus and place them on the baking sheet.
Drizzle the asparagus with half of the olive oil and season with a pinch of the sea salt and black pepper.
Roast the asparagus in the oven for 12-15 minutes until tender and slightly charred at the tips.
In a small bowl, whisk together the smoked paprika, garlic powder, onion powder, cayenne, and dried oregano.
Pat the salmon fillet dry with a paper towel and coat the flesh side generously with the spice rub, pressing it in to adhere.
Heat the remaining olive oil in a cast-iron skillet over medium-high heat until shimmering.
Place the salmon in the skillet, spice-side down, and sear for 3-4 minutes without moving it to develop a dark, flavorful crust.
Carefully flip the salmon and cook for another 2-3 minutes until the fish is opaque and flakes easily with a fork.
Remove from heat and serve the salmon alongside the roasted asparagus with a fresh squeeze of lemon juice over the top.