In a glass (non-reactive) bowl, stir together the halibut, lime juice, and lemon juice. Cover the bowl and marinate in the fridge for 30 minutes to 4 hours. You'll notice the halibut go opaque as the lime juice "cooks" the fish. The longer you marinate the fish, the more it will cook. See above in the blog post for more information.
Remove the halibut from the fridge (no need to drain it) and add the mango, avocado, jalapeno, red onion, cilantro, and salt. Gently stir it to combine.
Serve it up in individual glasses, on a plate, or with tortilla chips.