Bring a pot of salt water to boil and cook the potato chunks until very tender. Drain and return to their pot to steam dry. Preheat the oven to 375°F.

Heat a large skillet (non-stick if you have one that's oven-safe) over medium-high heat and add the potato and sausage chunks and some oil or butter. Cook, tossing occassionally, until the sausage and the potatoes are beginning to crisp, 5 to 6 minutes.

In the meantime, beat the eggs in a bowl with salt and pepper and slice the shallots. Add them to a bowl and cover with the lemon juice, a splash of olive oil, and a pinch of salt and pepper. Pinch with your fingers to dress and allow them to marinate, which will soften their raw harsh flavor.

Remove the sausage and potato chunks, leaving the oil behind, and add in the rosemary leaves. Cook them over high heat until just begining to crisp, then pour in the eggs. Add the sausage and potato chunks to the pan, distributing evenly, and slip the pan into the oven uncovered. Cook until the eggs puff up and are just lightly brown on top. Mix up the parsley with the shallots and scatter it over the pan. Serve immediately.