Heat oil in a large stockpot over medium heat. Add onion, carrots, mushrooms, celery, cabbage, bell pepper, garlic, and chili powder. Sauté until veggies soften, about 8-10 minutes.
Add corn, green beans, broth, and fire-roasted tomatoes, and bring to a boil. Reduce the heat and simmer for about 10 minutes.
Stir in lemon juice, then season with salt and pepper to your taste. Garnish with fresh chopped parsley and enjoy!