In a small bowl, whisk the lime zest, lime juice, tamari, salt, sherry, oil, mustard, honey, garlic and ginger. Place the fish in a small shallow preparation bowl and cover with marinade. Flip the fish so it lays skin side up and the flesh touches the marinade. Cover and refrigerate for 30 minutes to 2 hours before cooking.
Remove fish from fridge. Heat a 10-inch carbon steel or cast-iron skillet on high heat for about a minute. Add oil and allow it to coat entire surface of pan. Add fish skin side up and sear for 3-4 minutes. Flip fish, pour any remaining marinade over it and cook for 3-4 minutes to finish cooking. Total cooking time will be approximately 6-7 minutes (6-7 minutes per inch of thickness).
Remove from stove, top with remaining lime juice and parsley and enjoy.
Variation: Use the same marinade ingredients, but skip the tamari, sherry, and mustard and add a 1/2 teaspoon of sea salt for a simpler yet flavorful marinade.