Heat a 12-inch cast-iron skillet over medium-high heat.
In a small bowl, combine blackened seasoning and Italian seasoning; sprinkle mixture all over fish.
Add oil to hot skillet. Add fish; cook until blackened on bottom, about 5 minutes. Turn fish; cook until an instant-read thermometer inserted in thickest portion registers 145°, about 5 minutes. Remove from skillet.
Add lemons, cut side down, to skillet; cook until lightly browned, about 4 minutes. Serve fish with lemon. Garnish with oregano, if desired.
Notes
Kitchen Tip-Use a very well-seasoned cast-iron skillet for this recipe. Clean and dry it thoroughly to remove any acid from the lemons.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/blackened-grouper/