1. You can start by melting the butter in a large deep skillet or cast-iron pot and then saute the onions, vinegar, sugar, and a pinch of salt and pepper for about 5 minutes, or until the onions are tender and translucent.
2. You can now proceed to add the cabbage to the onion mixture and cook for 10 to 12 minutes, or until the cabbage softens and begins to brown.
3. To enhance taste, you season with salt and pepper.
4. Serve and enjoy

Watch this video recipe to know more about how to cook purple cabbage.