Preheat your grill or a heavy grill pan over medium-high heat to ensure a perfect sear.
In a small glass bowl, whisk together the olive oil, fresh lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper.
Pat the salmon fillet dry with a paper towel and brush both the salmon and the trimmed asparagus spears generously with the prepared lemon-herb marinade.
Place the salmon on the hot grill, skin-side down, and cook undisturbed for about 5 minutes until the skin is crispy.
Add the asparagus spears to the grill grates next to the salmon, turning them occasionally to achieve even charring.
Carefully flip the salmon fillet and grill for an additional 3 to 4 minutes until the flesh is opaque and flakes easily with a fork.
Remove the salmon and asparagus from the heat and allow the fish to rest for 2 minutes before serving to lock in the juices.