Peel the sweet plantains, use a many as you need. If they are much longer than 6 inches, cut them in half crosswise. Heat about ½ inch vegetable oil in a large, heavy skillet over medium heat. Add the plantains and fry, turning once or twice until softened, 4 minutes or so, depending how soft your plantains are to begin with. Remove and drain on paper towels. Hollow out the plantains, like a canoe, and fill the well with the pork picadillo filling. Arrange the canoes filling side up in a baking dish in which they fit snugly. Bake at 375°F until the filling is heated through, 20 to 25 minutes.