Put a large saucepan over a medium heat and add all your chopped and sliced vegetables. Mix together with a wooden spoon. Cook for around 10 minutes, oartially covered, until the carrots have softened aqnd the onion is lightly golden.
Grate the cheddar into a bowl and set aside. Put the stock cubes into a jug and add 1.8 litres boiling water. Stir until the cubes have dissolved, then add to the vegetables.Stir.
Bring to the boil then cover, reduce the heat and simmer for 10 minutes until the vegetables are tender.
Remove the pan from the heat. Season the soup, then add the cheese and mustard. Using a hand blender or a liquidiser puree the soup until smooth.