Prepare the Spice Rub: In a small bowl, combine the smoked paprika, dried oregano, onion powder, and fine sea salt. Mix until the spices are evenly distributed.
Season the Salmon: Thoroughly pat the salmon fillets dry with paper towels; removing excess moisture is crucial for achieving crispy skin with less salt. Generously coat the flesh side of each fillet with the spice mixture, pressing gently to adhere.
Heat the Pan: Place a 12-inch cast-iron skillet or heavy-bottomed stainless steel pan over medium-high heat. Add the avocado oil and heat for about 2 minutes, or until the oil is shimmering and flows easily across the surface.
Sear the Fillets: Carefully place the salmon fillets into the hot pan, skin-side down. Using a fish spatula, press down firmly on each fillet for 20 seconds to ensure the skin makes full contact with the pan. Cook, undisturbed, for 5 to 6 minutes, until the skin is deeply golden and releases cleanly from the pan.
Sauté the Aromatics: Flip the fillets to the flesh side. Reduce the heat to medium. Scatter the sliced shallot and grated ginger into the pan around the salmon. Pour in the unsalted vegetable stock to gently steam the aromatics and keep the fish moist without adding fat.
Finish Cooking: Continue to cook for another 2 to 3 minutes, or until the salmon is opaque and reaches your desired doneness (130°F–135°F / 54°C–57°C for medium). Drizzle the toasted sesame oil over the fillets in the last 30 seconds of cooking.
Garnish and Serve: Remove the salmon from the pan and transfer to a serving platter. Top with the chopped cilantro, mint, and fresh lime zest. Serve immediately with fresh lime wedges on the side.