Cut fish into small cubes and place into a glass dish.
Cover fish with lemon and lime juice. Cover bowl with saran wrap or lid and place in fridge for at least 4 hours.
After 4 hours, separate a cube of fish with a fork, checking to see if it is white all the way through. If there are any raw looking spots, recover, and check again in 30 minutes.
Once fish is completely white, drain in a colander.
In a separate bowl, mix together diced red onion, tomatoes, chili's, cilantro, avocado, tabasco sauce, and salt.
Gently fold in halibut and serve cold.