Prepare the sausages. Cut a slit down their length to pierce the skin. Then, remove the skin from the sausage (you will find that this act is profoundly freudian) and discard. You now have 3 naked sausages. Slice them into inch-thick chunks.
Boil some salted water and start the penne cooking.
Heat some olive oil in a separate pan. Sautee the onion, red pepper and garlic together until soft. Add the sausages in individual chunks (so they don't stick together) and brown them on a high heat. Season with salt and pepper.
Add a splash of balsamic and mix well. Add the tomato puree and mix to a deep, rich red colour. You'll want to eat it already but WAIT.
Add the diced tomatoes and heat through. Pour about a cup of boiling water in the pan, mix well and allow to reduce down - this will make sure the sausage cooks through, and helps to break down the tomatoes into a sauce.
By now your penne should be done. Drain and add to the meatball pan when the sauce looks nice and thick. Mix well, season to taste with salt and pepper, scatter the chopped basil on top and serve.