Shred the red cabbage, Napa cabbage, leek and onion in a food processor fitted with a slicing disc, or slice finely by hand. Grate the apples.
Heat 1 tablespoon of olive oil in a large, shallow ovenproof casserole dish over medium heat. Brown the bratwurst on all sides for 6 to 8 minutes – they do not need to be cooked through. Set aside.
Deglaze the dish with a splash of the beer, scraping up any browned bits.
Add the remaining olive oil, then the red cabbage, Napa cabbage, leek, onion and grated apple. Season with salt and pepper and cook, stirring, for 8 to 10 minutes. The dish will be very full at first but it soon wilts down.
Stir in the garlic and cook for 1 minute, then add the star anise, bay leaves, cinnamon stick, cranberry sauce, brown sugar, thyme and ground cloves.
Pour in the stock, the remaining beer and the apple cider vinegar and bring to a simmer.
Cover and cook in the oven for 1 hour, until the cabbage is very soft.
Stir in the drained lentils, then nestle the bratwurst on top, either whole or cut into 2 or 3 pieces on the diagonal.
Return to the oven uncovered for 20 to 30 minutes, until the bratwurst reach 160°F (71°C) in the center and most of the liquid has reduced.
Remove the cinnamon stick, star anise and bay leaves and serve sprinkled with fresh herbs.
Notes
Canned or dried lentils: I use canned lentils to keep this easy. To use dried instead, simmer 7 oz (200g) dried brown or green lentils in water or stock for about 20 minutes, until just tender, while the cabbage is in the oven. Drain and add them at step 9.Precooked bratwurst: Many store-bought bratwurst are already cooked. Brown them briefly and add them for the final 15 to 20 minutes only, so they heat through without splitting.As a side dish: Make it without the bratwurst – skip the browning step, braise the cabbage for 1 hour, then stir in the lentils and bake uncovered for 20 minutes. Serve with grilled sausages, pork chops or roast pork.Make ahead: It tastes even better the next day. Keep in the fridge for up to 3 days or freeze for up to 3 months.Recipe update: The original version of this recipe included cooking chorizo. The updated version leaves it out so the spiced red cabbage and bratwurst shine. To add it back, dry-fry 3½ oz (100g) diced cooking chorizo before browning the bratwurst, then stir it in with the lentils.Need to convert a measurement? Try my baking conversion calculator.