Dice the onion, carrot, celery, and potato into cubes.
Heat olive oil in a pot and sauté the onions.
Add the carrot, celery, and potato, and stir-fry together.
Add minced garlic for aroma.
Add tomatoes (or tomato sauce).
Pour in water or vegetable broth and bring to a boil.
Season with bay leaf, salt, and pepper.
Simmer over medium heat until the vegetables are cooked.
Serve the finished soup in a bowl.