Heat a little oil in a large pot over medium heat. Add the onion, carrot and celery, then sauté for 6–8 minutes until softened.
If using garlic, add it to the pot and cook for a further minute.
Stir in the diced tomatoes, tomato paste, salt, brown sugar, onion powder, garlic powder, dried basil and balsamic glaze or vinegar.
Pour in the vegetable stock. If using water instead, add the water along with the stock powder and stir well.
Bring to a gentle boil, then reduce the heat, cover and simmer for approximately 20 minutes, or until the vegetables are very soft.
Remove from the heat and blend with a stick blender until smooth. Alternatively, carefully blend the soup in batches using a regular blender.
Return the soup to low heat and stir through the cream. Warm gently without allowing the soup to boil.
Taste and adjust the seasoning if needed, then serve warm.