Scoop the halibut into a small bowl and pour in the lime juice. Stir to coat, then cover with plastic wrap and refrigerate for 1 hour, stirring several times to ensure the fish cures evenly. Drain the halibut and discard the lime juice.
Transfer the halibut into a large bowl. Gently fold in the tomatillos, olives, onion, jalapeno, avocado, cilantro and olive oil. Season with salt and the ceviche is ready to serve.