Sauté the onions: Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the chopped onion and cook, stirring occasionally, for about 6 to 8 minutes or until softened and lightly golden.
Add garlic and seasoning: Stir in the minced garlic, black pepper, and Italian seasoning (if using). Cook for an additional 1 to 2 minutes, until fragrant.
Brown the kielbasa: Add the sliced kielbasa sausage to the skillet. Cook for 5 to 6 minutes, stirring occasionally, until the sausage is browned on the edges and the onions are caramelized.
Add the cabbage: Stir in the chopped cabbage. Cover and continue cooking for 8 to 10 minutes, stirring occasionally, until the cabbage is wilted and tender, yet still retains a slight bite.
Season and serve: Season with extra salt and pepper, if needed. Serve hot with cooked white rice and beans on the side for a complete, hearty meal.