Cook pasta according to packet directions
Peel and dice onion, crush and finely chop garlic and dice chorizo.
Heat olive oil in deep frying pan on medium. Add onion and garlic and fry, stirring constantly, for 7 minutes or until soft and translucent.
Turn up to medium-high, add chorizo and fry for a further 3 minutes continuing to stir.
Add tomato paste, chilli flakes and oregano and fry for 2 minutes.
Turn heat back to medium, pour in tinned tomatoes and allow to simmer for 10 minutes or until slightly reduced. Season with salt and pepper and remove from heat.
Toss drained pasta through sauce to coat and serve topped with parmesan.