Make the homemade croutons - see recipe link above.
Coat a small Dutch oven with olive oil. Add the onions, carrots, and celery then place a lid on it. Cook, stirring occasionally, for 5-7 minutes or until the vegetables are tender; add the minced garlic and cook, stirring constantly, for 1 minute. Add the can of fire-roasted diced tomatoes, chicken broth, tomato paste, and sugar; season with sea salt and freshly cracked pepper, to taste. Cover with a lid and let it simmer for 30 minutes.
Blend the soup using an immersion blender until creamy and smooth then pour through a fine strainer, pushing with a spoon to remove all of the liquid from the pulp, into a large bowl. Side Note: I was in the mood for a smoother soup so I poured it through a fine strainer. If you are in the mood for a thicker and heartier soup, skip this step.
Pour the milk into the soup and stir until well combined. Taste and re-season with sea salt and freshly cracked pepper, to taste, if needed.
Top with homemade croutons and serve immediately. Enjoy.