Heat the oil in a large frying pan. Boil the kettle and pour the water into a large saucepan, then add the gnocchi and cook following pack instructions.
Meanwhile, roughly deseed and finely chop the chilli and slice the spring onions. Add them to the frying pan along with the tomatoes and vinegar, and cook for 5-6 minutes, until softened. Use a wooden spoon to gently squash the tomatoes.
Drain the gnocchi and add to the frying pan. Stir the gnocchi into the tomatoes and add the mozzarella. Give everything a good mix until the mozzarella is melted a little. Tear over the basil to serve.