Cut the cabbage, onion, carrot, celery, bell pepper, and tomatoes into bite-sized pieces.
Heat olive oil in a pot and sauté the onions.
Add the rest of the vegetables and stir-fry for 3~5 more minutes.
Add water, canned tomatoes, and salt, then bring to a boil.
Simmer on low heat for 20~30 minutes until the vegetables are tender. Your soup is ready.