FOR THE MARINADE: Combine all of the ingredients in a saucepan over medium heat. Whisk well and bring to a boil. Reduce the heat to medium-low and cook for 35 minutes. Set aside to cool.

Place the pork in a large plastic storage bag and pour in the marinade. Marinate for at least  8 hours and up to overnight in the refrigerator. Remove from the refrigerator and bring to room temperature. Transfer the pork loin, reserving the marinade, to a clean surface and pat dry. Season with the Essence or Creole Seasoning and rub the loin with 1/4 cup of the mustard.

Preheat the oven to 450 degrees F.

Place the pork loin on a roasting pan, and pour 1 cup of the reserved marinade over the pork. Roast for 10 minutes. Reduce the heat to 400 degrees F and continue to roast for 30 to 40 minutes, or until the internal temperature reaches 155 degrees F on a meat thermometer, basting every 15 minutes. Remove from the oven and let the loin rest for 10 minutes before slicing.

To make the sauce, bring the reserved marinade to a boil in a tall saucepan. Immediately reduce the heat to medium-low and simmer the marinade until it has reduced to 1 cup, about 20 minutes. Strain the marinade through a fine mesh sieve and return to it to a clean saucepan and bring to a simmer. Add the Creole mustard and simmer for 2 minutes longer. Add the butter a little at a time until the sauce has emulsified and thickens. Season and serve immediately with the pork loin.

Serve the pork loin with mashed sweet potatoes and collard greens.