Mix together the garlic powder, cumin and chilli powder then spread evenly onto both sides of the fish and season generously with salt and pepper.
Put the fish filet in the pan and cook for about 3-5 minutes depending on the thickness of your fish. Flip and cook for another 2-3 minutes on the other side.
While the fish cooks make the slaw by mixing together the shredded cabbage, green onions, mayo, cilantro and lime juice. Season with salt and pepper.
Heat up the corn tortillas according to package directions.
To serve the tacos, either flake the fish and serve family style alongside the slaw and any additional toppings, or build the tacos by adding some slaw and some fish to each tortilla.