Preheat your grill or grill pan to medium-high heat to ensure a good sear.
In a small mixing bowl, whisk together the olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper until well combined.
Trim the woody ends off the asparagus and place them on a tray next to the salmon fillet.
Brush the lemon-herb marinade generously over both sides of the salmon and coat the asparagus spears evenly.
Place the salmon on the hot grill, skin-side down, and cook for approximately 5 minutes without moving it to develop a crust.
Add the asparagus to the grill and carefully flip the salmon fillet.
Grill everything for another 3 to 4 minutes until the salmon is opaque throughout and the asparagus is tender with light char marks.
Remove from heat and let the salmon rest for 2 minutes before serving to lock in the juices.