Cut the cod fillets into uniformly sized pieces, between 3 and 5 inches long. Pat dry with a paper towel. To a small bowl, add the chili powder, ground cumin, dried oregano, smoked paprika, & garlic powder. Stir or shake to combine. Season the cod with the spice mixture, 1 1/2 teaspoons kosher salt, & ground black pepper as desired, ensuring you coat the entire surface of the fish. Set aside.
In a medium bowl, combine the shredded cabbage, diced mango, & sliced green onion. In a small bowl, combine the grated ginger, seasoned rice vinegar, & agave. Season with a pinch of salt. Set slaw and ginger dressing aside until serving.
Combine all listed ingredients in a food processor, seasoning with 1/2 teaspoon kosher salt and ground black pepper as desired. Pulse to break up the avocado & garlic, then blend until smooth & creamy. If necessary, add a couple tablespoons water to smooth out texture. Set aside, or store in an airtight container in the refrigerator for up to 2 days.
Just before placing the fish on the grill, generously oil a wad of paper towel. Use grilling tongs to run the oiled paper towel over the grill grates, generously oiling them. Place cod fillets directly on the grates. Cover & grill 3-4 minutes. Using a thin metal or fish spatula, flip the cod and continue to cook for 1-2 minutes, until cod flakes apart easily or the internal temperature reads 140 degrees F. Transfer fish to a clean plate.