Using a medium frying pan, brown chopped onion in olive oil for 3 minutes or  until tender. 
Sprinkle with smoked paprika; stir over low heat for 1 minute.
Turn up the heat and deglaze with apple cider and then the beef stock. 
Add the bay leaf and simmer for 5 minutes to reduce the sauce. 
Add chorizo and cook for 5 minutes; stirring constantly.
Pour in vinegar; stir well; serve hot and topped with chopped parsley.