Place cast iron skillet in oven and preheat to 500 degrees.
While the pan is heating in oven, sprinkle filets with seasoning on both sides.
**Turn oven off**, remove pan from oven, quickly place oil in skillet, then fish, then layer sliced tomatoes on top. Sprinkle with a bit more seasoning, if desired.
Quickly place skillet back into oven and cook for 5-6 minutes, then remove from oven and serve promptly. Enjoy!