In a small bowl, combine the garlic powder, onion powder, smoked paprika, oregano, basil, thyme, cayenne pepper, salt, and black pepper. Stir well until all the spices are evenly blended. This homemade mix will give your swordfish a fantastic flavor!
Pat your swordfish steaks dry with a paper towel. Then, generously coat both sides of each steak with the prepared spice mix. Gently press the seasoning onto the fish to ensure a good crust forms.
Place a large skillet (a cast iron skillet works wonderfully for this!) over medium-high heat. Add the butter or avocado oil and let it melt until it's hot and shimmering, but not smoking.
Carefully place the seasoned swordfish steaks into the hot skillet. Let them cook undisturbed for about 4-5 minutes, until a beautiful, dark "blackened" crust forms on the bottom. Resist the urge to move them too much!
Gently flip each swordfish steak to the other side. Continue to cook for another 4-5 minutes, or until the internal temperature of the thickest part of the fish reaches 145°F. This ensures your swordfish is flaky and moist inside.
Transfer the perfectly cooked swordfish to plates and serve immediately for a quick, healthy, and incredibly flavorful meal.