Pour the onions and white wine in a pot, bring to a boil and saute until half the wine evaporates. Boil the pasta in salted water.
Right before serving, pour the shrimp with the marinade into the pot with the wine, bring to a boil and add the fillet and fish broth.
After a minute remove from the heat. Add the pasta, parsley and tomatoes, stir and serve right away.