Preheat your grill or a heavy grill pan to medium-high heat.
In a small bowl, whisk together the lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper to create the rub.
Lightly brush the salmon fillet and the asparagus spears with the olive oil.
Apply the lemon-herb mixture evenly onto the flesh side of the salmon fillet.
Place the salmon on the grill, skin-side down, and cook for approximately 4-5 minutes.
Add the asparagus spears to the grill alongside the salmon, turning occasionally.
Carefully flip the salmon and grill for an additional 3-4 minutes until the fish is opaque and the asparagus is charred and tender.
Remove from the grill and serve immediately while hot.