Place a dry cast iron skillet or frying pan over medium high heat. Place the tortillas in the skillet to brown, about 10 seconds per side or until brown spots appear.
Remove the skin from your salmon and season both sides generously with blackening seasoning. (If you do not have any, mix paprika, onion powder, garlic powder, thyme, oregano, cayenne pepper, kosher salt and freshly ground black pepper.)
Add 1 tbsp of oil to the pan used to cook the tortillas, and then add the salmon, cooking 3-4 minutes per side.
While the salmon cooks, assemble the salsa. In a bowl, combine the oranges, avocado, onion, cilantro, lime, and salt to taste. Mix to combine.
To assemble, use a fork to flake off chunks of the cooked salmon. Place on the tortilla, topped with 1-2 tablespoons of the salsa and a sprinkle of crumbled queso fresco. Squeeze a wedge of lime over each taco and sprinkle with a few cilantro leaves. Serve immediately