Melt butter in warm pan. Add the eggs and season with salt and pepper.
Cook until the whites are almost set, then carefully flip the eggs.
Season again with salt and pepper, and let cook fully, about 30 more seconds.
As the eggs cook, cook sausage.
Toast both slices of bread.
Spread avocado on one side of the bread, season with salt and pepper to taste. Assemble and enjoy!