They only look like bull horns. They are genuine vegetables.
Place them straight onto a high naked flame on the stove or barbecue. Using tongs, turn them over every couple of minutes. They will blister and then turn black. Once they are black remove them from the flame, place them on a board and remove the charred skin with a butter knife. The skin will peel or scrape off easily.
You can add salt and pepper or olive oil, but without any other additions, they are good to go as they are.