Heat a grill or broiler to medium high.
In a small bowl, whisk together 1 tablespoon of the oil, 1½ teaspoons of the lime juice, and the jerk seasoning. Rub this mixture over the pork and grill or broil the meat until browned all over, 2 to 3 minutes per side (6 to 8 9 minutes total). Reduce the heat to medium (or move the pork to a lower-heat area), close the lid if grilling, and cook until the meat is just firm (145°F internal temperature), 6 to 8 minutes more. Transfer it to a cutting board and let it rest for 5 minutes.
Peel the oranges by running a knife all around each one to remove the entire rind down to the flesh. Working over a large salad bowl to catch the juices, hold each peeled orange in your hand and run the knife on either side of each segment in a V shape to remove it from the bitter membrane; set the segments aside. Squeeze the empty membrane over the bowl to extract 2 tablespoons of orange juice. Whisk the mustard, curry powder, salt, and remaining 1 tablespoon of lime juice into the orange juice. Add the remaining ¼ cup of olive oil in a slow, steady trickle, whisking, until thickened. Pour out ¼ cup of the dressing and set it aside. Add the greens, pepper, and scallions to the bowl with the dressing that’s left and toss to coat. Divide the greens among four salad plates and arrange the mango and reserved orange segments over the top.
Slice the pork and drape it over the top of the salad. Drizzle with the reserved dressing.
Tip: If your jerk seasoning doesn’t include sugar or salt, add 1 teaspoon of brown sugar and ½ teaspoon of salt to the rub mixture along with the seasoning.