Preheat oven to 450°.
Cut one piece of parchment paper roughly double the size of the fish. Then cut into the shape of a heart, making the heart as large as possible given the size of the paper you originally cut. In the center, arrange cilantro, green onion, and ginger. Place fish on top, leaving 1/2" from the center crease. Sprinkle fish with soy sauce and pepper, then top with butter.
To close the paper heart, start at the top and turn over the paper so that each fold is made to the end of the heart and the next one overlaps the previous. Done correctly, they will hold each other closed. When you get to the bottom, twist the paper tightly and tuck it under. Bake for 10 minutes, or until fish reaches the desired doneness. Fully cooked fish should not resist or feel firm when pierced. Serve with rice, farro, or potatoes.