Cut onion, carrot, celery, cabbage, and bell pepper into bite-size pieces.
Heat olive oil in a pot and sauté the onion.
Add carrot, celery, bell pepper, and cabbage in order, and stir-fry.
Pour in canned tomatoes and water, then bring to a boil.
Season with bay leaf, salt, and pepper.
Simmer over medium-low heat until the vegetables are cooked through.
Serve in a bowl.