- In a medium, nonreactive bowl, combine fish, lime juice, and onion. (Use enough juice to cover fish completely.) Cover and refrigerate until fish no longer looks raw when broken open, about 4 hours.
- In a large bowl, toss tomatoes, jalapeño, and cilantro with olive oil. Stir in fish and season with salt. Stir in coconut milk and sugar. Mix in avocado just before serving.