In a lidded pan large enough to fit the mussels, put a splash of oil, heat it up, add the vegetables, and let them fry for a couple of minutes—watch that they do not brown. Season heartily, as you still have the mussels and wine to come, and add the thyme then your mussels and the wine. Stir so they all get to meet the mixture, place the lid on the pan, and cook the mussels, now and then giving the pan a shake. When the mussels open they are cooked. Remove from the heat and allow to cool. When cool pluck the mussels from their shells, and strain and reserve the liquor.