Heat the olive oil in a large pot over medium heat.
Add the onion, and cook until translucent, stirring so it doesn't catch.
Add the garlic, carrot and celery, and cook for about 10 minutes until soft. Deglaze the pot with a bit of water, if needed.
Stir in the tomato paste and sugar.
Add the vegetable stock and tomatoes (both canned and fresh), and stir.
Cook on low heat for abot 25 minutes, stirring occasionally.
Blend with an immersion blender, and season to taste with salt and pepper.
Serve with a garnish of parsley (optional) and enjoy!