To begin, prepare the red cabbage by removing the outer leaves and the core. Finely shred the cabbage using a sharp knife or mandolin slicer. Place the shredded cabbage in a large bowl and sprinkle with a tablespoon of red wine vinegar. Toss well and let it sit for 10 minutes to soften slightly.

In a large, heavy bottomed pot, heat the butter or vegetable oil over medium heat. Add the chopped onion and sauté for 3-4 minutes until translucent. Stir frequently to avoid browning, as the onion should retain its sweetness.

Add the grated apple to the pot with the onions. Cook for another 2 minutes, stirring occasionally. The apple will add a natural sweetness to balance the tanginess of the vinegar.

Gradually add the shredded cabbage to the pot, stirring to combine with the onion and apple mixture. Cook for 5 minutes, allowing the cabbage to begin wilting. This ensures the flavours meld as you add subsequent ingredients.

Pour in the apple juice (or water) and the remaining red wine vinegar. Add the sugar, cinnamon stick, cloves, and bay leaf. Stir gently to mix the spices evenly through the cabbage. Adjust the liquid amount slightly if the cabbage looks too dry, as it should simmer in a bit of liquid.

Reduce the heat to low, cover the pot with a lid, and let the cabbage simmer gently for 40-50 minutes. Stir occasionally to prevent sticking, and check that the cabbage remains moist. If needed, add a splash of apple juice or water.

Season the Rotkohl with salt and black pepper to taste. Taste the cabbage to ensure a balance of sweet, sour, and savoury flavours. Adjust the sugar or vinegar as needed to suit your preference. Remove the cinnamon stick, cloves, and bay leaf before serving.

Serve the Rotkohl warm as a traditional side dish. It pairs beautifully with roasted meats, sausages, or potato dumplings. For an authentic presentation, garnish with a sprig of fresh parsley or a slice of apple. This dish can be made ahead, as the flavours deepen when reheated the next day.