Preheat your grill or a cast-iron grill pan over medium-high heat and lightly coat with a small amount of oil to prevent sticking.
In a small mixing bowl, whisk together the lemon juice, lemon zest, finely chopped parsley, garlic powder, sea salt, and black pepper to create the herb rub.
Brush the salmon fillet and the asparagus spears evenly with the extra virgin olive oil.
Rub half of the lemon-herb mixture onto the flesh side of the salmon fillet, pressing gently so it adheres.
Place the salmon on the grill skin-side down and cook for 4-5 minutes, then carefully flip and cook for another 3-4 minutes until the center is just opaque and flaky.
Add the asparagus to the grill alongside the salmon during the last 5-6 minutes of cooking, turning occasionally until they are tender and show light char marks.
Remove from heat and drizzle the remaining lemon-herb mixture over the salmon and asparagus before serving immediately.