Pat the salmon filets dry with paper towels or a clean kit towel. Season liberally on all sides with kosher salt and set aside while you make your spice blend. \nIn a small mixing bowl, stir together the paprika, brown sugar, 1 teaspoon each salt, onion powder, garlic powder, oregano and ½ teaspoon cayenne. \nIn a separate mixing bowl, combine the diced avocado, mango, red onion, lime juice, a drizzle of olive oil and ½ teaspoon salt. Gently mix to combine. Season to taste with salt and additional lime juice, as desired. Set aside until ready to serve. \nDrizzle the flesh side of the salmon with canola oil. Sprinkle with the blackening spice blend, lightly pressing down to thoroughly coat the dish. \nCoat a large oven-safe skillet (or 2 smaller skillets) with a drizzle of canola oil and heat over medium-high\/high heat. Once the pan is very hot and the oil is shimmering, carefully place the salmon in the pan(s), skin side down. Press down lightly on the flesh side as you hear the salmon sizzle. \nContinue cooking, undisturbed, over medium-high heat, until the skin begins to turn golden brown and crisp up, about 2-3 minutes. If the edges of your salmon start to fold in, gently press on the fish with a spatula to ensure even browning. \n\nOnce the skin is golden brown and crispy, flip the fish over. Let cook on the flesh side for about 2-3 minutes more for medium-rare doneness, Or, cook over high heat for about 1-2 minutes, allowing the flesh side to get a golden-brown sear, then reduce the heat to medium\/medium-low and continue cooking until cooked through to desired doneness.