1Place the chopped tomatoes, onion, garlic, basil, water and olive oil into a saucepan and bring to the simmer. Add a good pinch of salt and sugar. Reduce heat and allow to simmer very slowly for 1 1/2 hours.
2Place in a blender and blend until velvety smooth. Return to the pot and reheat. Toss in the olives and chorizo.
3Blanch the pasta in boiling water for 2 – 3 minutes, toss through the sauce and serve topped with grated Parmesan.