Add the oil to a large skillet with lid. Add the spicy mustard, vinegar, and sausage and stir together. Saute for a few minuteswhile you chop the veggies.
Chop the cabbage and onions. Add to the skillet and saute for 4-5 minutes or until the cabbage has wilted and cooked. Season with salt and pepper to taste.
Warm bread or prepare other sides.
Serve Kielbasa & Cabbage Skillet with preferred sides.