Heat the oil in a medium pan over a medium heat. Fry the onion and garlic for 8-10 mins until soft. Add the chorizo and fry for 5 mins more. Tip in the tomatoes and sugar, and season. Bring to a simmer, then add the gnocchi and cook for 8 mins, stirring often, until soft. Heat the grill to high.
Chorizo & mozzarella