In a large bowl, whisk together the pineapple juice, rum, molasses, thyme, ginger, cayenne, salt and garlic powder. Add the pork slices, turning to make sure that all surfaces are coated with the marinade; cover and refrigerate for at least 1 hour.
In a 5-quart non-stick saucepan, heat the extra virgin olive oil over medium-high heat. Add the onions, peppers, plantains, and pecans; cook until the plantains start to caramelize and turn brown, about 5 minutes. Using a slotted spoon push the mixture to the outside rim of the pan; arrange the pork tenderloins in the center of the pan and pour over the marinade. Cover the pan and cook until the pork is tender, opaque and no longer pink, about 15 minutes.
Divide the pecan plantain salsa between 4 warmed plates; arrange the pork slices on top and drizzle with the sauce remaining in the pan. Serve immediately.
NOTE: Ripe plantains will be yellow with black spots, NOT green