Begin the ragu. If using fresh gnocchi, start preparing them after the ragu has been set to simmer.
For Fresh Gnocchi:
Heat the oven to 350° F degrees. Pierce the potatoes with a fork and bake until soft, or for about 90 minutes. While still hot, cut the potatoes in half and scoop out the middle. When cooled, pass the potato through a potato grater. Add the white pepper and then the egg yolk. Add about 1 cup of flour to the mixture. Mix thoroughly with a fork or pastry cutter and then form a ball. On a well-floured work surface, knead and fold mixture until the flour is incorporated, adding another 1 to 2 cups along the way. The dough should not feel sticky, so add a little more flour if necessary. Cover with flour and let rest for five minutes. Divide dough into 8 pieces. Roll out each piece into a long tube of about 1 inch thick and then cut into lengths about 1 inch long. Next, use a fork to make each piece into the shape of gnocchi, by rolling each piece up and down the tines of the fork. (If you do not plan to use the gnocchi within an hour or so, freeze them until ready.)
For the Ragu
In a large skillet, over medium heat, heat 2 tablespoons of olive oil. Add the short ribs and sear all sides. Remove from heat.
In a large pot, over medium heat, sauté the onion in the olive oil until golden. Add the short ribs, and after a couple of minutes, add the tomato, salt and pepper to taste. Reduce the heat to low and simmer for 2 hours, stirring regularly, until thickened and meat is tender or is incorporated into the sauce. If too thick, add a bit of water so that the meat can continue to simmer until tender.
Bring a large pot of salted water to a boil.
Cook the gnocchi and drain. Place the pasta in a serving bowl and coat with sauce. Serve with grated Parmigiano.
Remove the ribs to a separate platter, and serve alongside or after the pasta.
1 pound gnocchi (fresh or frozen) will work for this recipe.