In a very large heavy-based saucepan or wok, heat the oil and saute the garlic, onion, spices and ginger for 3 minutes. Once the onion is cooked, increase the heat, add the cabbage and toss continually to coat in the oil and spices.
Reduce the heat to low and add the apple cider vinegar and apple concentrate. Cook for another 6 minutes, season, then remove from the heat - the cabbage should still be crunchy.
Stir through the grated apple and walnuts and serve immediately.