Cook the spaghetti in salted water.
While the noodles cook, shell and lightly chop the salted duck eggs. Put in the blender or food processor with the extra virgin oil, sun-dried tomatoes and pepper. Process until smooth. Add the basil. Pulse a few more times.
Heat the butter in a frying pan. Add the chopped chorizo and cook over medium-low heat for a minute or two.
Add the cooked pasta to the chorizo. Toss well.
Pour the salted duck egg sauce over the pasta. Toss well. Taste.
Ladle the salted duck egg and chorizo spaghetti into bowls, garnish with snipped scallions and serve at once.