Mix the sugar, vinegar and peppercorns in a small bowl. Place racks in upper and lower thirds of oven; preheat to 400°. Line 2 rimmed baking sheets with foil and fit with wire racks. Place bacon on racks and sprinkle with half of peppercorn and sugar mixture. Bake 15 minutes, turn, sprinkle with remaining mixture, and rotate baking sheets. Bake bacon until brown and crisp, 15–20 minutes longer.