Preheat oven to 425 degrees.
In a shallow dish, combine flour, cornmeal, lemon pepper, and salt.
Dredge the fish in the flour mixture to coat on all sides and shake off any extra, by tapping the fish lightly.
Heat a cast iron pan over high heat. Add the butter and olive oil. When the pan is very hot, add the cod and cook the first side for about 2 minutes, or until golden. Carefully flip the fish and cook for another 1-2 minutes while spooning the butter mixture over it. Place in the oven and cook for 5-7 minutes while you make your sauce.
Add the lemon and orange juice to a small pan over high heat and reduce the liquid to about half. Pour the juice into a small bowl and set aside.
Using the same small pan, heat 1 tbsp of butter in a saucepan and cook the garlic over medium heat until translucent, about 1-2 minutes. Be careful not to get color on the garlic, or it will ruin the taste of the sauce.
Add the wine, turn the heat up to high, and cook until you have reduced it to about half.
Reduce the heat to medium low.
Using a whisk, slowly mix in 1 tbsp butter at a time, adding more as it becomes emulsified and thickened. It is important that the butter is room temperature so the sauce doesn't break.
Continue adding the butter until you have a nice, thickened sauce.
Add the citrus reduction and salt, and mix well.
To serve, drizzle the sauce over the cod and enjoy!