Supreme the orange. Don't know how? Read the post for a link and the reason why. Believe me, you can do it. It's easy.
Separate the supremes into two equal portions.
In a medium bowl, juice one half of the orange.
Cut the other half of the orange into 1 - 1.5" pieces and set aside.
Add lime juice, serrano (see notes), oil, salt, pepper, and cilantro, (reserve a little for garnish), to the bowl with the orange juice and whisk together.
Very gently toss in the avocado, mango, and orange supremes.
Cover the bowl with plastic wrap or a lid and refrigerate for an hour.
Serve sprinkled with additional cilantro leaves and coconut, if using.
Enjoy!