For the cocktail sauce, pour the orange soda into a bowl and add salt to taste, preferably about 1/4 teaspoon or just enough so it's barely noticeable (it shouldn't taste salty).

Whisk the soda until it loses its carbonation (the foam disappears), then add 1/2 teaspoon ground black pepper and the ketchup. Mix well until everything is fully combined.

In a glass or cup of your choice, add the shrimp, cocktail sauce, onion, cilantro, and top with avocado.