Heat a grill to medium high heat, 400 - 450 degrees. Add a grill pan to the grill grates for easier control when cooking the fish.
Pat fish dry and then rub with olive oil.
Season with salt, pepper and red chile powder
Once the grill and grill pan are hot. Add the fish fillet. turn the heat down to medium. If the fillet has skin, place the fillet flesh side down and sear until lightly browned. Turn the fillet over and simply close the lid and let the fish cook for about 15-20 minutes or until fish starts to flake. This time all depends on the size and the thickness of the fish.
If the fish fillet has no skin, turn once while cooking. See notes below for more details
In the meantime, heat your corn tortillas. Warm the corn tortillas by wrapping them in a damp paper towel and cooking them in the microwave for for 2 minutes at 50% power.
Remove the fish to a platter and flake the meat into pieces.
Once the tortillas are warm and steamy, build your tacos by placing 1/4 of the fish onto two taco shell. Add toppings of your choice. Suggestions: Cotija Cheese, slices of avocado, red onion, or pickled red onions, a squeeze of lime juice and cilantro.