Egg and sausage is the egg sandwich that has left the lunchbox and joined the breakfast. The other eggs on this shelf are cold and bound, chopped hard-cooked egg held with a dressing and eaten at midday. This one is hot and whole: a fried egg and a cooked sausage in a roll, read as a fried breakfast folded into bread rather than as a salad. That reading changes everything about it. The egg is not a bound filling but a structural element with a yolk to manage, and the sausage is the load-bearing flavour, savoury and fatty and warm, with the egg there to soften and enrich it rather than to be the point.
The craft is heat, grease, and the yolk decision. The sausage is cooked through and browned so its fat renders and its skin takes colour, then split or laid whole so it sits flat in the roll instead of rolling out of it. The egg is fried to a deliberate finish: a set yolk makes a tidy, portable sandwich, a soft yolk makes a sauce that coats the sausage and binds the build but commits the eater to a roll that runs. Either is right, but it has to be chosen rather than discovered. The bread is a soft floured roll that can absorb a little rendered fat and yolk without disintegrating, and brown or red sauce, when it goes in, goes inside and in a measured stripe so it seasons rather than floods. Butter on the roll bridges the salt of the sausage to the wheat.
The variations are the rest of the breakfast roll, each a swap inside the same hot fried-breakfast frame. Bacon stands in for or joins the sausage; black pudding adds an iron, peppery note; the egg banjo strips it back to a fried egg alone with the yolk deliberately loose. Each deserves its own article rather than being crowded in here.