Parboil the potatoes until they are almost cooked through, drain and set to one side.
While the potatoes are cooking, heat the oil in a frying pan and cook the shallots until they start to soften. Squeeze the sausages out of their skins and make them into little sausage balls. Add them to the hot pan, cook for a few minutes then add the potatoes and cook everything together until golden and crispy, you may need a little more oil.
Sprinkle over the chilli flakes and parsley and season. Keep warm while you fry the eggs in a little butter.
Serve the eggs on top of the hash, with mustard and ketchup on the side.