Best recipe I have for ceviche, obtained from a local, is:

soften the conch by hitting it repeatedly with an empty Belikin bottle or some such instrument; put it in a deep bowl

dice up carrots, tomatoes, onions and a little garlic and add it to the conch. Dice as much habanero pepper and add it to spice it up to taste

squeeze a bunch of limes and put the juice in the bowl; you'll need lots of juice, because that's what cures/"cooks" the conch. I add a little beer to increase the volume of fluid

let it sit in a refrigerator for 24 hours, after which it's ready to eat