2 pounds Idaho potatoes
2 large egg yolks
1/2 cup all-purpose flour
1/3 cup semolina flour
sea salt
freshly ground black pepper
Cook the potatoes with their skins on in a large pot of boiling salted water. Drain and peel while hot. (The potatoes must be very dry and hot for successful gnocchi.) Put the potatoes through a potato ricer and into a bowl, or mash with a potato masher. Lightly fold in the egg yolks, all-purpose flour, semolina and salt and pepper, then work together quickly by hand to obtain a dough. Divide the dough into 4 parts.
On a clean work surface, roll out each piece of dough into a long roll shape, a little fatter than your index finger. Cut into 1-inch lengths. Roll each small piece over the back of a fork to make indentations, which will catch a bit of the sauce.
Bring a large pan of salted water to a boil. Add the gnocchi and cook over high heat until they rise to the surface. Remove with a slotted spoon, letting the spoon rest on a clean folded cloth to drain off any excess water. Place in a shallow bowl and spoon over the sausage and tomato sauce. Finish with the remaining Parmesan cheese and serve.
