Mix the cabbage, onions, cilantro, green onions, and pepper in a bowl. Squeeze in lime and season with salt. Set aside.
Griddle Cod
Trim the ling cod if necessary so it is ready to cook. Season with blackening seasoning and salt. Spray with oil.
Preheat the griddle to 375 degrees F (190 degrees C), then oil.
Add the ling cod to the griddle and cook for about 3 minutes. Turn and cook the other side until browned and cooked through. The cooking time will change depending on the thickness of the cod.
To Serve
Spray corn tortillas with oil then lightly season with salt. Cook them on the grill until char marks form. Turn the tortillas and continue until the other side is also marked.
Make each taco by adding to the tortilla the grilled ling cod then top with the slaw. Feel free to top with your favorite taco condiments like salsas, sauces, and more grilled chilies.