Heat olive oil in a large pot over medium heat. Add the onion and sauté until translucent.
Stir in the garlic, leeks, celery, and carrot, cooking for 3 more minutes.
Add the red bell pepper, zucchini, and potatoes, stirring to combine. Let them cook for a few minutes to release their flavors.
Pour in the chopped tomatoes and vegetable broth. Add the bay leaf and thyme. Bring the soup to a boil, then reduce heat and let it simmer for 20-25 minutes, or until the vegetables are tender.
Remove the bay leaf, season with salt and black pepper, and garnish with fresh parsley. Serve hot and enjoy!