Finely slice the onion.

Fry the onion in vegetable oil over medium heat for about 15 minutes, stirring frequently, until softened and slightly caramelized.

Slice the chorizo into half-moons.

Remove the papery skin from the chorizo if desired.

Add the chorizo to the caramelized onions, increase the heat, and cook until the onions turn orangey and the chorizo crisps up.

Drain off some of the oil, reserving some for flavor.

Cook the pasta according to package directions in a large pot of boiling water.

As the pasta cooks, add the tomato passata and sun-dried tomato puree to the frying pan.

Reduce the heat and simmer the sauce gently, stirring frequently, until it thickens.

Once the pasta is cooked, drain it and combine it with the sauce.

Season to taste.

Sprinkle with nutritional yeast (or parmesan cheese) before serving.