Peel three or four well-ripened tomatoes, remove the seeds and the surrounding gelatinous part and cut the flesh into pieces.
Fry the guanciale cut into strips in a medium-large frying pan, as it will also be used to sauté the pasta (it is fried over a medium-slow heat and without the need for oil, as there is more than enough to go around).
When it is crunchy, add a splash of dry white wine and let it reduce, that the alcohol evaporates.
Remove the guanciale and fry the onion cut into small squares and the cucumber, crumbling up the juice left in the paella.
When the onion is golden brown, add the tomato pulp to the pan.
After 7 minutes, taste the sofrito and add salt if necessary.
When the sofrito is ready, add the bucatini al dente to the paella with a ladle of its cooking water.
Sauté the pasta for 20 seconds, add the guanciale, and sauté the pasta for half a minute more.
Serve the pasta with a little grated pecorino on top. Place a bowl of grated pecorino on the table, in case anyone wants to add more to the pasta.