Add sausage to preferably a larger pot. Cook until brown and done. Drain grease and set aside in a bowl.
Add the olive oil, leeks, carrots and celery to the pan. Best to keep any bits from the sausage in the pan too while cooking this. Sauté for 5 minutes, stirring occasionally. Then add the cabbage and garlic. Sauté for 5 more minutes, stirring occasionally.
Add the stock, potatoes, Italian seasoning, cooked sausage, and stir to combine. Continue cooking until the soup reaches a simmer. This can go longer pending how the potatoes are cooked.
Taste and season with salt and black pepper as needed. This step you can add more Italian seasonings pending how flavorful the sausage is.
Serve warm. Will last 2 to 3 days refrigerated in a sealed container. We also have froze this soup and will last 2 to 3 months.