In a large pot, place the octopus along with the wine, peppercorns, 1 lemon cut in half, and garlic. Cover with water by 1 inch and bring to a boil over medium high heat. Reduce the heat to a simmer, and cook the octopus until it is tender when pierced with a sharp knife. (Anywhere from 45 to 90 minutes.) Drain, and allow the octopus to come to room temperature.
set the burners of a gas grill to high heat. Set cooking grate in place, cover grill and allow to preheat for 5 minutes. Clean and oil the grilling grate. Toss the octopus with 1/4 cup of the olive oil and season with salt and pepper. Place the octopus on the grill and cook for a few minutes on both sides until the octopus is well browned, but still remains moist, 3 to 4 minutes per side.
Cut the octopus tentacles, place on a platter and squeeze some lemon over top. Serve immediately or at room temperature with lemon wedges and a sprinkle of cilantro.