Preheat a gas grill to medium-high heat and lightly brush the grates with oil.
In a mixing bowl whisk together 1 tablespoon olive oil, 1 tablespoon lime juice, ancho chili powder, ground cumin, onion powder, paprika, ground coriander, 1/2 teaspoon salt, and 1/2 teaspoon black pepper to make the rub.
Rub the spice mixture evenly over both sides of each salmon portion.
Place salmon on the preheated grill and cook until opaque and cooked through, about 3 minutes per side, rotating once halfway through.
While the salmon cooks, make the avocado salsa by gently tossing diced avocado, rinsed diced red onion, chopped cilantro, minced jalapeño, minced garlic, 2 tablespoons lime juice, 1 tablespoon olive oil, and salt and pepper to taste in a bowl.
Warm the corn tortillas if needed, then break the cooked salmon into small pieces and divide among the tortillas.
Top each taco with shredded cabbage, avocado salsa, and a sprinkle of crumbled Cotija cheese, then serve warm.