Potato hash with Italian sausage and good cheese

600g waxy potatoes, peeled and cut into chunks

1 red onion, thinly sliced 

1 medium Italian sausage (fennel & chilli) or Chorizo 

handful of parsley leaves, chopped 

small handful of pine nuts 

150g hard sheep’s' cheese like Cais na Tire 

50g butter 

olive oil 

sea salt

black pepper