Prepare the vinaigrette by combining olive oil, red wine vinegar, mustard, garlic powder, and salt and pepper in a small jar. Shake until well combined.

Brown the kielbasa in a large skillet with olive oil for 5–7 minutes until golden brown.

Sauté diced onion in the skillet for 5 minutes after adding it to the cooked kielbasa.

Add chopped cabbage to the skillet and sauté for 8–10 minutes until tender, seasoning with salt and pepper.

Combine the cooked cabbage and kielbasa with half of the prepared vinaigrette, stirring gently.

Serve warm, garnished with fresh herbs and additional vinaigrette if desired.