Start by preparing the filling. Remove the sausage case and place them in a bowl. Add the grated Parmigiano Reggiano, breadcrumbs and dried fennel flowers. Mix the ingredients with your hands: if they are too dry, add a tablespoon of extra virgin olive oil.
Now cut open the loin. Working on the short side of the loin, first cut it open like a book, going from right to left, and then go back, to the right. You have to make an S-shaped incision.
Open the loin on a cutting board, or on a sheet of parchment paper, and season with salt and pepper. Place the filling on the pork loin and press it well with your hands. You might want to leave an inch without stuffing on the short edges of the pork loin, as it will be easier to roll it.
Wrap the pork loin on itself, starting from the short side, pressing well as you roll it up, taking care that the filling remains well sealed inside.
Now tie the pork loin with the butcher's twine: cut many pieces of string long enough to tie the loin on the short side, about 1 inch apart. Stringete bene i nodi, legando la lonza ogni 2 cm, così da formare un cilindro ben compatto. If you have them, place a few fennel flowers under the string, it will release its wonderful aroma while cooking. Season the loin with salt and pepper, then rub the seasoning into the meat.
Pour the extra virgin olive oil into a pan large enough to hold the pork loin. Be generous, depending on the size of the pot, you could use several tablespoons of olive oil.
Heat the olive oil over medium heat.
When the olive oil is hot, place the pork loin into the pan. Sear the meat it over medium heat until it becomes golden brown, then turn it with two wooden spoons, so as to brown it on all four sides. It will take about ten minutes.
When the pork loin is golden brown on each side, pour a cup of white wine over it. Reduce for a few seconds, then immediately cover the pan with a lid. The moisture of the wine will cook the turkey.
Move the pot over very low heat and cook the pork loin for about 30 minutes, checking towards the end to prevent it from drying too much. If you have moved the pan to very low flame, there should be no problems.
Now turn off the heat and let the pork loin rest in the pan for at least an hour. Thus, the residual heat of the pan will finish to cook the pork, leaving the meat juicy and tender. Do not skip this part, otherwise the pork will not be cooked properly.
Now you can choose whether to serve the pork loin immediately or wait until it is completely cold. If you prefer thin and neat slices, wait until the next day and stash the pork in the refrigerator.
Once the pork loin is cold, it will be much easier to slice it. To warm it, do not heat the pork itself, which would otherwise become too dry.
Heat a serving dish and place the sliced pork loin on top, then heat the cooking sauce on the pan and pour it over the meat. This will be enough to warm it up.