Step 1Heat the oven to 450 degrees.
Step 2Peel the papaya with a sharp knife or vegetable peeler. Cut the papaya in half lengthwise and scoop out and discard the seeds. Place the papaya halves cut side down and cut in 1/2-inch slices. Set aside.
Step 3Cut the ginger root lengthwise into rectangles about 1/4-inch thick. Stack the rectangles and cut them into thin matchstick pieces. Cut the pieces in half lengthwise. Set aside.
Step 4Cut 4 pieces of heavy-duty foil about 6 inches longer than the fish filets. Spray the foil lightly with nonstick spray. (If you're using regular foil, stack together 2 pieces, shiny side down, for each packet.)
Step 5Place each filet on a piece of foil, season with salt and pepper and spoon 3 tablespoons of orange juice over the top. Divide the papaya slices among the fish, setting them on top so they're overlapping slightly. Place the ginger pieces on top and sprinkle with the shallots.
Step 6To seal the packets, bring the long sides of the foil up over the fish and fold the edges. Fold again, crimping the foil to form a tight seal. Press the foil to the fish. Double-fold the ends in toward the fish. Be careful not to tear the foil.
Step 7Place the packets on a baking sheet and bake until the fish flakes with a fork, 15 minutes. Carefully unfold one end of the packet, letting the steam escape. Then open the top. Sprinkle with the cilantro and serve.