Cook the sausages according to packet instructions. Put a pot of salted water on for the pasta.
Heat the oil over a medium heat and add the onion and pepper and cook until softened. Add the garlic, oregano, balsamic and tomato puree and cook for another couple of minutes then pour in the chopped tomatoes, add the sugar and bring to a simmer. Cook for about 10 minutes.
While the sauce cooks add the pasta to the boiling water and cook according to packet instructions. Slice the sausages.
Remove a mugful of pasta cooking water before draining the pasta. Add the pasta and the mugful of pasta water to the sauce and toss together. Serve with grated parmesan.
Nutrition information is an estimate and will vary depending on the exact ingredients used.