In a small bowl, whisk together 0.5 tbsp of the olive oil, the lemon juice, chopped dill, chopped parsley, garlic powder, 0.25 tsp of the sea salt, and 0.25 tsp of the black pepper.
Place the salmon fillet in a shallow dish and pour the herb marinade over it, ensuring the fish is well-coated; allow it to marinate for 10 minutes.
Preheat your grill or a cast-iron grill pan to medium-high heat.
Trim the woody ends off the asparagus and toss the spears with the remaining 0.5 tbsp olive oil, 0.25 tsp sea salt, and 0.25 tsp black pepper.
Place the salmon on the hot grill, skin-side down first, and cook for 4-5 minutes per side until the flesh is opaque and flakes easily with a fork.
Add the asparagus to the grill alongside the salmon during the last 6 minutes of cooking, turning occasionally until tender and lightly charred.
Remove from heat and serve the salmon immediately with the grilled asparagus and an extra squeeze of fresh lemon if desired.