Put oven racks in upper and lower thirds of the oven. Line 2 large shallow pans (17x11") with foil. Put pans in oven and preheat oven to 500 degrees. Pat the wings dry, then toss with oil, salt, and pepper and divide between preheated pans, spreading wings in 1 layer. Roast, without turning, until golden and tender, about 35 minutes. While wings roast, simmer vinegar, soy sauce, and sugar, stirring occasionally, until reduced to about 1/3 cup, about 12 to 14 minutes. Remove from heat, and stir in butter until melted. Remove wings from oven and let staned 1 minute, then transfer to a large bowl. Pour balsamic mixture over the wings and toss to coat well. Let stand for 5 minutes, then toss again.