Speedy Tomato Soup - Pinch Of Nom

Ingredients

• low-calorie cooking spray
• 1/2 onion, (peeled and chopped)
• 2 large carrots, (peeled and sliced)
• 2 large potatoes, (peeled and chopped into chunks)
• 1 stick celery, (sliced)
• 800 ml boiling water
• 2 vegetable stock cubes
• 400 g tin chopped tomatoes
• salt and freshly ground black pepper