If using fresh tuna, cook and flake it. If using canned tuna, drain and flake it.
In a bowl, combine the grated coconut, finely chopped onion, green chilies, and tomato.
Add the flaked tuna to the bowl with the other ingredients.
Add lemon juice, salt, and black pepper. Mix well until everything is evenly combined.
Garnish with fresh coriander or mint if desired.
Enjoy your meal!