Chop halibut into small 1/2 inch by 1/2 inch cubes.
Soak the halibut and onions in the lemon and lime juice, make sure they are fully covered. Let marinate for 4 hours.
After 4 hours, remove from citrus and strain well.
In a separate bowl, mix the remaining 1 teaspoon lemon juice, coconut milk, ginger juice, garlic and sea salt together.
Pour this mixture over the halibut and add the cucumber and cilantro. Gently toss everything together well.
If needed, season more to taste.
For fun, serve in a half avocado!