Shred the green cabbage finely with a cheese slicer, sharp knife or in a food processor.
Fry the cabbage in about half of the butter (or substitute olive oil) in a large frying pan or wok on medium heat for about 10 minutes, or until just softened.
Add vinegar, salt, onion powder, and pepper. Stir and fry for 2-3 minutes, or until well incorporated. Reserve sautéed cabbage to a bowl.
Heat the rest of the butter or oil in the pan. Add the garlic and leeks, and sauté for a minute.
Add meat, and continue frying until cooked through. Sauté until most of the liquid has evaporated.
Add tomato paste and mix well. Lower the heat a little and add reserved cabbage and fresh basil. Stir until cooked through.
Adjust seasoning and serve with a dollop of sour cream or mayonnaise and perhaps even a green salad.