Preheat your grill or grill pan to medium-high heat.
In a small bowl, whisk together the olive oil, lemon zest, lemon juice, dried oregano, garlic powder, sea salt, and black pepper to create a marinade.
Brush the herb mixture generously over all sides of the salmon fillet and the trimmed asparagus spears.
Place the salmon on the grill, skin-side down, and cook for 4-5 minutes without moving it to ensure a good sear.
Add the asparagus spears to the grill alongside the salmon, turning occasionally.
Carefully flip the salmon and grill for another 3-4 minutes until the fish flakes easily with a fork and the asparagus is tender and slightly charred.
Remove from the heat and serve immediately while the salmon is hot and the citrus aromas are at their peak.