In large pot or Dutch oven, heat olive oil over medium heat. Add chopped onion and cook until softened and translucent, about 5-7 minutes. Add minced garlic and cook for another minute until fragrant.

Add shredded cabbage, diced carrots, and diced celery to pot. Stir well and cook for 5-7 minutes until slightly softened.

Pour in crushed tomatoes and stir well to combine.

Pour in vegetable broth (or chicken broth). Add oregano, thyme, smoked paprika, red pepper flakes (if using), salt, and pepper. Add bay leaf. Bring to boil, then reduce heat to low, cover, and simmer for at least 30 minutes, or up to an hour, stirring occasionally.

If using sausage, add diced cooked sausage during last 15-20 minutes of simmering. If using potatoes, add diced potatoes during last 20-25 minutes of simmering.

Stir in apple cider vinegar. Taste and adjust seasoning as needed. Remove bay leaf.

Ladle soup into bowls and garnish with fresh chopped parsley.