Heat the oil in a large saucepan and cook the onion for 2-3 minutes until it begins to soften. Add the garlic and cook for another minute.
Tip in the chorizo and cook for 3-4 minutes until it starts to become fragrant and season well. Stir through the chilli flakes and pepper, then add the passata. Bring to the boil and add the linguine.
Turn down to a simmer and cook for 8-10 minutes, or until the pasta is just al dente. Add a splash of water while cooking if the sauce is too thick. Stir through the prawns until heated through, and then serve with the fresh parsley.