To prepare the Mahi-mahi:
Brush the mahi with melted butter. Season both sides of the fish with thyme, salt and pepper. Set aside covered.
To Prepare the red wine sauce:
In a medium sauce pan, add 2 tablespoons of butter along with the carrot, celery, onion, spices and remaining salt and pepper. Cook over high heat until the vegetables are well browned and caramelized. Add the red wine, stock and port. Bring to a boil and simmer to reduce the sauce until about 1 cup of liquid remains. Mix the flour together with the 1 tablespoon of butter. Strain the sauce into a small pan and whisk in the flour mixture, a little at a time until thickened and the sauce has a clean gloss.
To cook the Mahi-mahi:
In a heavy bottomed pan, heat the remaining butter. As it starts to sizzle add in the fish skin side down to begin. Cook for 3-4 minutes on medium high heat and then turn the fish. Cook the second side for another 2 minutes. Add a tablespoon of the res wine sauce to glaze the mahi-mahi..
Pour the sauce in the center of the plates and place the mahi-mahi just off center to the circle of sauce.