1.Finely chop the onions, garlic, carrot and celery. Cut the leek into rounds. Preheat a saucepan over a medium heat and add a glug of olive oil. Tip in the veggies and sauté with a pinch of salt for 5-6 mins. Tip in the tomatoes, Parmesan rind and stock. Bring to a simmer and let blip away for 10-15 mins.