In a bowl, mash the avocado with a fork until smooth. Mix in the lime juice and cilantro. Season with salt and pepper to taste. Toast the bread and spread the avocado mixture on top.
Preheat a non-stick pan over medium low heat. Add the butter. Crack eggs on a flat surface and into the pan being careful not to break the yolk. Cook until the whites of the eggs start to become firm. Season with salt and pepper.
Pour the coffee over ice and prepare to your liking.
Serve the eggs with avocado toast and iced coffee.