Place a 30cm or 12" frying pan on a low-medium heat, add a splash of oil, and when it warms a little, add the sausages. Roll the sausages back and forth for the first 3-4 minutes, slowly heating the sausage skin all over without colouring or searing it. After the first few minutes, increase the heat to medium-high and cook for another 10-12 minutes, constantly moving to get a nice even colour.
Generously butter each piece of bread on one side.
Heat a third 24cm or 10" frying pan over a high-medium heat with enough oil to form a 2-3mm (⅛") layer on the base of the pan.
When the oil is hot, crack the eggs into the pan and add a pinch of salt to each and a generous pinch of black pepper. Cook for 2-3 minutes, flip and cook for a final minute. This will deliver a beautifully runny yolk but a white with a nice frilly "skirt".
Cut the sausages in half lengthways and place them on the bread, add a squirt of your favourite sauce, followed by a fried egg, a little more sauce and then tuck in. Breakfast is served.