Pat the salmon fillets dry with paper towels and season both sides with sea salt, onion powder, and black pepper.
Heat 3 Tbsp avocado oil in a large 12-inch stainless steel or cast-iron skillet over medium-high heat until shimmering.
Carefully place the salmon fillets flesh-side down in the hot skillet and cook 2–3 minutes, until the sides start to turn opaque.
Flip the fillets and cook the second side about 2 minutes; reduce heat to medium or medium-low if the pan is smoking or the salmon browns too quickly.
Add the minced garlic, lemon zest, lemon juice, and chopped parsley to the skillet and gently stir or spoon the mixture around the fillets to combine flavors.
Cover the skillet and continue cooking 2–5 minutes, until the salmon reaches your desired doneness (opaque and flaky throughout).
Remove from heat and serve immediately with your preferred side dishes.