Add your salmon fillets to a shallow dish along with the soy sauce, sesame oil, garlic, ginger, chili, and green onions. Season with pepper and toss the salmon around to evenly coat. Set aside at room temperature to marinate for 10 minutes.
Meanwhile, heat a large cast iron skillet over medium-high heat.
Add a little neutral oil to the pan and remove the salmon from the marinade, scraping off most of marinade. Add the salmon, skin side down, to the pan and cook, undisturbed, for 5 to 6 minutes.
Using a fish spatula or metal spatula, flip the fish and continue to cook for 2 minutes or until cooked through to your liking.
Serve immediately skin side up to ensure it stays crispy for as long as possible.
