Preheat your grill or grill pan to medium-high heat.
Finely mince the garlic clove and chop the fresh dill and parsley.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, dill, and parsley to create the marinade.
Season the salmon fillet and the asparagus spears with the sea salt and black pepper.
Brush half of the lemon-herb marinade over the flesh side of the salmon fillet.
Place the salmon on the grill, skin-side down, and cook for 4 to 5 minutes.
Add the asparagus to the grill alongside the salmon, turning occasionally.
Carefully flip the salmon and brush with the remaining marinade, grilling for another 3 to 4 minutes until the fish is opaque and flakes easily with a fork.
Remove the salmon and asparagus from the grill and serve immediately with an extra squeeze of fresh lemon if desired.