Bring a large pot of salted water to the boil. Cook the spaghetti according to packet directions until al dente. Before draining, reserve 250ml (1 cup) of starchy pasta water. Drain and set aside — it will be added to the hot sauce in the final step.

Heat the oil in a large 12-inch (30cm) frying pan over medium heat. Add the diced onion and cook for 3-4 minutes until softened and translucent. Add the minced garlic and cook for a further 30 seconds until fragrant.

While the onion cooks, squeeze the sausage meat from each casing and roll into small balls — aim for about 3 per sausage (roughly walnut-sized). Discard the casings.

Push the onion to the edges of the pan and increase the heat to medium-high. Add the meatballs in a single layer, leaving a little space between each. Cook without moving for 2-3 minutes until the undersides are golden brown, then turn and brown the other side for another 2 minutes.

Add the diced carrot and frozen peas to the pan. Stir and cook for 2-3 minutes until the carrot has softened slightly and taken on a little colour.

Pour in the balsamic vinegar and toss everything together. Let it bubble and reduce for 60-90 seconds, stirring occasionally, until the vinegar has nearly evaporated and left a dark, sticky glaze on the meatballs and vegetables.

Pour in the chopped tomatoes and stir well. Season with salt and pepper to taste. Bring to a gentle simmer and cook for 4-5 minutes, stirring occasionally, until the sauce has thickened slightly.

Add the drained spaghetti to the pan and toss through the sauce and meatballs using tongs. If the sauce feels too thick or the pasta looks dry, add a splash of the reserved pasta water (a few tablespoons at a time) until everything is well coated and glossy.

Divide between warmed bowls. Top with freshly grated or shaved Parmesan and torn fresh basil leaves. Serve immediately.